AU782544B2 - Method for improving water quality of tank systems - Google Patents

Abstract

A method is described for improving water quality or correcting and adjusting important chemical parameters of the water in biological tank systems, such as aquaria (warm, cold, fresh or salt water), garden ponds, carp pools, water gardens and large aquaria (zoos, public aquaria) whereby the following are added to the tank system individually or arbitrarily combined: a) for reduction of phosphate concentration, at least one highly or poorly soluble Al<3+>, Fe<3+>, TiO<2+>, ZrO<2+> or Ca<2+> salt of an organic carboxylic acid, optionally mixed with an organic carboxylic acid; b) for reduction of nitrate concentration or limiting nitrate increase, at least one water soluble N-free biologically degradable organic compound; c) for an increase in carbonate hardness or the HCO3<-> concentration, at least one alkali or earth alkali metal salt of an organic carboxylic acid; d) for an increase in total hardness or the concentration of Ca<2+> and Mg<2+> hydrogen carbonates, a mixture of at least one Ca<2+> and Mg<2+> salt of organic carboxylic acids and e) for an increase in CO2 concentration at least one biologically degradable compound and an appropriate single- or multi-component product.

Description

PD-6235 Process for the improvement of the water quality of maintenance waters The invention concerns individual processes for the improvement of the water quality or correction and adjustment of important chemical water parameters of biological maintenance systems with use of ecologically neutral, chemically- and microbiologically-acting water additives, a combination of several processes for the improvement of the water quality in biological maintenance systems, as well as a single or multiple component product hereby usable.

In biological maintenance systems, e.g. aquaria, aquatic terrains and garden ponds, due to the daily feeding of the fish and other aquatic animals kept therein, it results in cumulative changes of important chemical water parameters and consequently in a continuous impairment of the water quality.

From this follows a correspondingly reduced quality of life of the maintained fish and other aquatic animals.

If the starting water, e.g. tap water, possesses a sufficient quality, then, by frequent partial or complete change of water, an impairment of the water quality caused by the maintenance can be countered. The procedure of the water change is laborious and unpleasant for the aquarianists, for the maintained fish and other aquatic organisms not without, in part, considerable endangering due to undesired properties of the fresh starting water, such as for example chlorine or heavy metals.

Consequently, a minimising of the water change frequency and amount would be desirable.when as described in the present invention it succeeds to suppress or to eliminate the impairment of the water quality.

In detail,lit comes, in biological maintenance systems, to the following changes of important water parameters impairing the water quality. This is countered, in part, by already known measures.

A) An example for such changes is the increase of the phosphate concentration by continuous introduction with the feed. The phosphate increase to values above 10 mg/l is disadvantageous since the undesired algal growth is promoted by phosphate.

The following measures are known for the phosphate reduction: a) Binding of phosphate to A13+ and/or Fe 3 oxides (hydroxide group-containing granulates) which are introduced into the filter s.ystem. Disadvantageous is their limited capacity. After their exhaustion, it is necessary to change the granulates, which is frequently very laborious. If the aquarianist does not regularly measure the phosphate content, he will not recognise the exhaustion of the material and the PO3- concentration in the maintenance water will again increase, i.e. the treatment success of this method is frequently only insufficient.

b) In the case of regular use, the addition of dissolved inorganic A13+ and/or Fe 3 salts also leads to a lowering of the P0 4 3 concentration.

Disadvantages of this process are: high fish toxicity of the dissolved inorganic A13+ and Fe 3 salts, enrichment of the water with anions, such as e.g.

chloride and sulphate, reduction of the carbonate hardness, of the HC03and C0 3 2 content and thus reduction of the buffer capacity, lowering of the pH level and danger of the acid fall at KH 0' dH, turbidity of the water and unpleasant flocculation of Al(OH) 3 and FE(OH) 3 B) A further example for the said undesired changes is the increase of the nitrate concentration by continuous introduction of proteins and other sources of nitrogen with the feed. All sources of nitrogen originating from the feed, to the greater part proteins, are oxidised microbially via ammonia and nitrite to nitrate. The continuous nitrite increase represents an unnatural loading of the maintenance water which is undesired for the aquarianist. Frequently, the nitrate content of the starting water is already so high, e.g. at 25 50 mg/l, so that the natural N03- concentration of a few mg/l is never achievable by change of water.

The following measures are known for the lowering of the nitrate content: a) Lowering of the nitrate content by anion exchangers, mostly in chloride form. Disadvantageous is hereby the replacement of the nitrate ions by the loading anions of the exchanger, mostly chloride, and the replacement of sulphate and hydrogen carbonate ions.

Besides the undesired lowering of the carbonate hardness, the chemical water composition is completely changed.

b) Denitrification in anaerobic medium or in anaerobic reactors. By introduction of practically insoluble, biologically decomposable organic, nitrogen-free **material in granulate form into the filter system, by means of strong 02 consumption, anaerobic regions are provided in which nitrate, as source of oxygen, is reduced to N 2 Disadvantageous is: the uncertain dosing, the uncertain process control and process controlability, the sulphate reduction to be expected in the case of small N0 3 concentrations to highly toxic hydrogen sulphide.

C) The lowering of the carbonate hardness caused by nitrification forms a further example for the mentioned undesired water changes. The oxidation of the continuously supplied organic nitrogen proceeds via the oxidation of ammonia to nitrite made possible by nitrifying bacteria.

In the case of this biological process, one mol H ions result per mol of ammonia. The liberated H ions react with bases present, mostly hydrogen carbonate as former of the carbonate hardness, with protonisation and reduction of the carbonate hardness.

For the compensation of the carbonate hardness losses (or HCO3- losses) but also for the increasing of the carbonate hardness, the following measures are known: a) Addition of NaHCO 3 and/or Na 2

CO

3 as powder or as solution. The process functions dependably but involves the following disadvantages: In the case of NaHCO 3 /Na 2

CO

3 mixtures, it results in rapid pH increases in the maintenance water which lead to considerable stress of the organisms.

In waters with increased ammonium contents, parallel to the pH increase inter alia a lethal amount of ammonia is liberated.

The water solubility of NaHCO 3 is relatively low so that highly concentrated liquid products with convenient use are not possible.

b) Addition of freshly prepared solutions which, besides dissolved calcium hydrogen carbonate, also contain much free CO 2 The excess CO 2 can lead to a rapid CO 2 damaging of the organisms. Besides the HCO 3 concentration, the Ca 2 concentration is here also increased, which is not always desired.

Furthermore, chemically and biologically caused losses of dissolved calcium hydrogen carbonate can bring about 7 undesired water changes. Due to CO 2 consumption and the pH increase connected therewith, the lime/carbonic acid equilibrium is displaced in the direction of lime precipitation. The disadvantageous loss of dissolved Ca(HCO 3 2 leads to a corresponding lowering of the calcium concentration and of the HCO 3 concentration (carbonate hardness lowering).

For the compensation of the losses of Ca(HCO 3 2 or its increasing, the following measures are known: a) Addition of solutions which, besides Ca(HCO 3 2 still contain free CO 2 This measure is encumbered with the above-described disadvantages. A further disadvantage lies in the laboriousness of the process since the Ca(HCO 3 2 solutions must be laboriously prepared by dissolving of CaCO 3 or Ca(OH) 2 in C0 2 -enriched water. By addition of Mg(OH) 2 or MgCO 3

*MG(OH)

2 a solution can also be prepared which contains additional Mg(HCO 3 2 b) Addition of solid mixtures which contain equivalent amounts of NaHCO 3 and soluble Ca, Mg salts (mostly chlorides). By dissolving of these mixtures in maintenance water, the ions Ca 2 2 Cl- 2 Na 2 HCO3are introduced. Besides the desired [Ca 2 2 HCO 3 the water now contains the equivalent amount of NaCl (or also Na 2

SO

4 which is undesired. The disadvantage of this process consists in the introduction of foreign salts, e.g. NaCl or Na 2

SO

4 Finally, a consumption of dissolved carbon dioxide also changes the water quality.

Algae, water plants and autotrophic microorganisms continuously require dissolved carbon dioxide. Besides the pH value thereby increased, a CO 2 deficiency situation also results which acts disadvantageously on chemical and biological processes.

For the compensation of the CO 2 deficiency, the following

CO

2 addition measures are known: a) Addition of CO 2 gas from CO 2 pressure bottles.

Problematical in the case of this method are: the difficultly adjustable and controllable dosing, the price, the safety risks which are involved with the pressure gas system, b) CO 2 production by anodic oxidation of a graphite electrode. The system contains the following disadvantages: poor dosability,

CO

2 peaks due to secondary chemical processes on the cathode, involved with a strong decalcification, formation of oxyhydrogen gas, formation of chlorine in chloride-enriched waters.

c) Production of CO 2 in external formation reactors. Here, too, serious, system-caused disadvantages exist, e.g.

strong temperature dependency of the fermentation process, difficultly controllable.process, very poor dosing possibility and dosing constancy.

9 The various described problems initially appear to be heterogenous and not solvable with one principle.

Surprisingly, however, for all partial problems there exists a common solution which includes the following chemical and microbiological principles: Utilisation of the microbiological activity of the water and especially of the filter systems in the maintenance systems which include the aerobic and anaerobic processes.

Use of components, products and compositions which are biologically decomposable in part or completely.

Linkage of microbiological and chemical processes in the maintenance system.

Use of components, products and compositions which not only fulfil the desired function but introduce no undesired additional materials or allow them to accumulate.

Use of components, products and compositions which are completely safe for fish and other aquatic organisms.

All products and methods behave ecologically neutral and lead to no secondary impairments of the water quality.

All promoting functions are alone very simple to handle and make possible dosed water additions.

Thus, the subject of the invention is a process for the improvement of the water quality of biological maintenance systems, which is characterised in that to the maintenance system one adds singly or in combination a) for the lowering of the phosphate concentration, at least one easily or sparingly soluble A13, Fe 3 TiO 2 ZrO 2 or Ca2+ salt of an organic carboxylic acid, possibly in admixture with an organic carboxylic acid; b) for the lowering of the nitrate concentration or limitation of the nitrate increase, at least one watersoluble N-free, biologically decomposable organic compound; c) for the increasing of the carbonate hardness or of the HC0 3 concentration, at least one alkali metal or alkaline earth metal salt of an organic acid; d) for the increasing of the total hardness or of the concentration of Ca2+ and Mg2+ hydrogen carbonates, a mixture of at least one Ca 2 and Mg 2 salt of an organic carboxyiic acid and for the increasing of the C02 concentration, at least one biologically decomposable compound.

Furthermore, the subject of the invention is a single or multiple component product for the improvement of the water quality of maintenance systems for the functional, causal use according to need, characterised by a content (singly or in combination) of at least one easily or sparingly soluble A13 Fe 3, TiO2+, Zr2+ or Ca 2 salt of an organic carboxylic acid, possibly in admixture with an organic carboxylic acid; at least one water-soluble, N-free biologically decomposable organic compound; at least one soluble alkali metal or alkaline earth metal salt of an organic carboxylic acid, and a mixture of at least one Mg2+ and Ca2+ salt of an organic carboxylic acid.

The consistent use and linking of the maintenance system as microbiological and chemical reactors for the achievement of the desired water improvement from simple added precursors is novel and also not obvious for the expert and, because of the simplicity, of the controllabl and commanding processes and of the complete absence of potentially damaging side effects and actions, brings considerable and innovative advantages in comparison with the solutions of the prior art. An especial advantage of the invention is also to be seen in the fact that it makes possible a separate or common solution of the described partial problems.

In the following, the detailed solutions according to the invention are described: A) Lowering of the phosphate concentrations This preferably takes place with salts of A13 Fe 3 and TiO 2 or Zr2+ with organic carboxylic acids, e.g. with their acetates, formates, tartrates and especially citrates, Besides the strongly phosphate-binding metal ions A13+, Fe3+ TiO 2 ZrO 2 there can also be used calcium salts of organic carboxylic acids in similar manner, however with considerably smaller phosphate elimination ability. Mixtures of salts of organic acids with the basic organic acids and other organic acids are also usable with the same effect, e.g.

aluminium citrate plus citric acid, iron (III) citrate plus citric acid, iron (III) citrate plus tartaric acid.

Furthermore, it is also possible to add sparingly-soluble salts of the said metals with organic acids in solid form (powder, granulate, tablets) as depot phosphate eliminators to the filter system or generally to the maintenance system.

The principle is illustrated in the following for A13' and Fe3+ salts but applies correspondingly also for TiO02 and ZrO 2 salts. If A13+ and/or Fe3+ salts of carboxylic acids are added to the maintenance water, initially no flocculation and turbidity is observed. Only in the case of aerobic biological decomposition in the filter system according to aluminium citrate (Al3+) 3HC03aerobic decomposition iron (III) citrate (Fe3+) CO 2 In the case of direct subsequent formation of Al(OH) 3 or Fe(OH) 3 according to 13 Fe 3 (Fe (OH) 3) 3HCO3- 3CO 2 Al 3+ (Al (OH) 3) is phosphate added on and precipitated out together with the hydroxides.

The metal hydroxides precipitated out with co-flocculated phosphate collect in the filter sludge and are eliminated in the case of the regular filter cleaning.

By means of regular addition of organic metal salts, e.g. as aqueous solution, to the maintenance water, the phosphate increase can be completely prevented.

In contradistinction to the phosphate precipitation with inorganic A13+ or Fe3+ salts, the phosphate precipitation according to the invention contains serious and surprising advantages: no turbidity and flock formation results in the water, the process takes place substantially in the biologicallyactive filter system, the organic metal salts behave toxicologically neutral, ecologically neutral, carbonate hardness neutral, no enriching foreign ions are added, by aerobic decomposition of carboxylic acid anions, only

CO

2 is produced, which positively influences the CO 2 content or compensates the CO 2 consumption in part.

The resulting phosphate concentrations are typical for each metal: for Fe citrate: about 0.0 0.2 mg/l, for Al citrate: about 0.0 0.5 mg/l, for Ca citrate: about 0.5 1.5 mg/l.

Very good phosphate elimination successes are achieved when, weekly or two weekly; 1 mg/l to 100 mg/l, preferably 10 mg/l to 40 mg/l aluminium citrate, iron citrate or their mixtures are added to the maintenance water. The phosphate elimination action is dependent upon the introduced amount of metal cation.

B) Lowering of the nitrate concentration or limitation of the NO 3 increase by N-free, soluble organic compounds.

If N-free, organic, decomposable substances are added regularly to the maintenance water, also without the presence of anaerobic reactors, the increase of the nitrate concentration is slowed down or limited and a nitrate concentration is achieved which levels out at an average level. Without treatment with these water additives according to the invention, the nitrate content increases ever further monotonously and unlimitedly. Since the reason for the hindered or limited nitrate increase lies in a partial denitrification in the anaerobic microregions in the filter, parallel to the slowing down, limitation of the nitrate increases, the nitrification-caused loss of carbonate hardness (HC03- concentration) is also inhibited or limited.

As nitrate-reducing, water-soluble compounds, in principle all biologically decomposable organic compounds can be used but preferably aliphatic compounds, such as for example alcohols; e.g. glycerol, sorbitol, ethanol, sugars, e.g.

pentoses, hexoses, saccharose, carboxylic acids, e.g. acetic Acid, citric acid, lactic acid and tartaric acid.

Combinations of in each case equal part amounts of citric acid and saccharose or acetic acid and saccharose have also proved to be very useful.

If, to the maintenance water, one adds three times a week or every two days 5-100 mg/l, preferably 5 40 mg/1 of the acid compounds or mixtures, then the nitrate increase is slowed down and, in relation to the selected dosing, definite nitrate highest concentrations are no longer exceeded.

Dosing examples for the combination citric acid/saccharose .are: a) 3 dosings per week with 10 mg/l [citric acid plus saccharose nitrate limiting concentration: 60 mg/l b) 3 dosings per week with 20 mg/1 [citric acid plus saccharose 40 mg/l.

In the case of higher dosings, e.g. 60 100 mg/l three times weekly or more frequent lower dosings, e.g. daily 10 mg/l, the nitrate limitating concentration can be lowered still further, e.g. to 5 10 mg/l N3-.

16 Parallel to the N03- stabilisation, there is also achieved a stabilisation of the carbonate hardness at minimum values below which the carbonate hardness does not sink furter.

The added compounds are completely broken down to H 2 0 and

CO

2 The CO 2 formed is used by plants, algae and nitrifying bacteria as C-source.

By introduction of an aeration, the CO 2 concentration, can be corrected downwardly according to need.

C) Increasing of the carbonate hardness or of the HCO 3 concentration In the case of the solution according to the present invention, one makes use of the following microbiological/chemical principle with the use of Na Ca 2 Mg 2 and Sr 2 salts of aliphatic carboxylic acids, such as e.g. acetic acid, lactic acid, citric acid, tartaric acid, formic acid, propionic acid, malic acid and the like.

If carboxylic acids, e.g. acetic acid, are decomposed microbiologically, there results only H 2 0 and CO 2 02, decomposition

CH

3 COOH 2CO 2 2H 2 0 If, on the other hand, one subjects salts of the carboxylic acids to the microbiological decomposition, then, besides CO 2 corresponding to the number of the introduced negative charges of the anions, hydrogen carbonate is also formed: 17 02, decomposition

CH

3 COO-

CO

2 1,5 H 2 0 HCO3- By the introduction of salts of carboxylic acids into the maintenance water, after biological decomposition, the hydrogen carbonates are formed.

On the example for sodium hydrogen carbonate from organic sodium salts, e.g. Na acetate, Na citrate, this may not act very spectacularly since NaHCO 3 itself is easily accessible.

However, even here, in the case of liquid composition, the great advantage exists of the mostly in comparison with NaHCO 3 very high solubility, for example Na acetate which permit high product concentrations and ranges.

A further advantage of the use of organic Na salts instead of NaHCO 3 or Na 2

CO

3 consists in the pH neutral use: The Na salt of organic acids acts pH neutral, with excess carboxylid acid(s) can even be adjusted acidic in the product. This is naturally not possible with NaHCO 3 or Na 2

CO

3 In the case of biological decomposition (apart from in the case of formates), CO 2 still results which also counters a pH increase.

The advantages of the problem solution according to the invention are still better recognisable when one considers the introduction of the hydrogen carbonates of the alkaline 2+ 2+ 2+ earth metal, Mg 2 Ca 2 Sr 2 which, as known, are not available as substances. By addition of the soluble Mg2+ Ca2+ Sr 2 salts of organic carboxylic acids, the desired 18 concentrations of the hydrogen carbonates can be built up in the maintenance water without problems.

Example: (acetate) 02, decomposition

M

2 (OAc) 2

M

2

(HC

3 2 2C0 2 3H 2 0

M

2 Mg 2 Ca 2 Sr 2 The dosing is orientated to the desired adjustment or increase of the carbonate hardness or of the HC0 3 concentration. 1 mMol/l Na salt of organic carboxylic acids increases the carbonate hardness by 2.8 0 dH, 1 mmol/l Mg2+, Ca 2 Sr 2 salts of organic carboxylic acids increases the carbonate hardness by 5.6 0 dH.

The alkali metal or alkaline earth metal salts of the organic carboxylic acids can be added to the maintenance water in solid form (powder, granulate, tablets) or in the form of aqueous solutions.

As carboxylic acids, there can be used: a) for Na+ salts: practically all aliphatic carboxylic acids, especially acetic acid, lactic acid, citric acid, tartaric acid and the like.

b) for Mg2+ salts: practically all aliphatic carboxylic acids, especially acetic acid, lactic acid, citric acid, tartaric acid and the like.

c) for Ca salts: all aliphatic carboxylic acids which form water-soluble Ca 2 salts, especially formic acid, acetic acid, propionic acid, lactic acid, malic acid and the like.

d) for Sr2+ salts: all aliphatic carboxylic acids which form water-soluble Sr 2 salts, especially formic acid, acetic acid, propionic acid, lactic acid, malic acid and the like.

D) Increasing of the total hardness or of the concentration of Ca 2 and Mg 2 hydrogen carbonates The principle of this problem solution according to the invention and all important details of use were described under The advantages of the method and of the composition are: very simple and sure, defined adjustment and increase of the total hardness, problem-free preparation and use of product compositions, especially liquid solutions, no introduction of undesired foreign ions, easy adjustment of all desired Mg:Ca ratios from oo:l to 1:00.

2b only controlled amounts of COz are produced which serve for the C-supply for plants, algae and autotrophic microorganisms.

besides the here-described Mg 2 and Ca 2 hydrogen carbonates formed from organic salts, other inorganic Mg2+, Ca 2 salts, such as e.g. chlorides or sulphates, can also be added in combination so that every possible or required chemical composition of the total hardness can be realised.

E) Increasing of the C02 concentration In the preceding problem solutions A) to it has already been described that, In the case of the biological breakdown of organic compounds, C0 2 is formed in the maintenance system. This can be built up to an internal, microbiologically-working C0 2 supply system. A continuous and sufficient but still not organism-damaging supply of C0 2 to the maintenance water fulfils various important functions: carbon fertilising of the plant organisms, carbon supplying of the autotrophic micro-organisms, especially of the nitrificants, prevention of the pH increase caused by C02 consumption, adjustment of a definite pH value by adjustment of the HC0 3 /C0 2 acid-base equilibrium, intervention in the lime/CO 2 equilibrium and prevention of the chemical and biological lime precipitation.

It has been shown that COz concentrations between 1 and mg/l, preferably 5 15 mg/l, lie in the optimum range.

Potential CO 2 damagings of fish and other water organisms do not occur here. Since CO 2 is continuously used up in the maintenance system and losses emerge into the atmosphere, CO 2 must be dosed in the correct amount to the maintenance water.

This can be achieved very easily by a daily or every two day dosing to be carried out of biologically decomposable organic compounds, e.g. of aliphatic organic carboxylic acids, alcohols and sugars. The following compounds have proved to be especially useful: a) carboxylic acids: formic acid, oxalic acid, acetic acid, lactic acid, citric acid, malic acid, tartaric acid, b) alcohols: ethanol, glycerol, sorbitol, c) sugars: pentoses, hexoses, saccharose.

If one doses the carboxylic acids alone, then, in a chemical reaction, from the hydrogen carbonate supply, the equivalent C02 amount is immediately liberated: HC0 3

CH

3 COOH CO 2

H

2 0 CH 3

COO-

In the case of the subsequent biological breakdown of the carboxylic acid anion, the consumed hydrogen carbonate.is 22 slowly again produced (within a few hours up to 24 hours) and further CO 2 formed:

CH

3 COO- HCO 3

CO

2 1.5 Consequently, carboxylic acids produce CO 2 in a stepped process: a) in a secondary reaction by,protonisation of HCO3-, b) in a reaction lasting a few hours up to 24 hours by oxidative biological breakdown.

Alcohols and sugars added to the maintenance system are subsequently broken down to H 2 0 and CO 2 in a relatively slow microbiological reaction.

By choice of combinations of different C-sources with different speeds of the CO 2 liberation, a very uniform CO 2 introduction can be achieved, e.g. by the combination of citric acid and saccharose or acetic acid and saccharose. The individual compounds or combinations are dosed as follows: daily 1 20 mg/l, preferably 3 10 mg/l or also every 2 days 2 40 mg/l, preferably 6 20 mg/l.

The water improvement agent according to the invention can be used for the individually defined function purposes of use in all biological maintenance systems, such as e.g.

23 aquaria (warm water, cold water, fresh water, salt water), garden ponds, koi ponds, aquaterrains, large aquaria (zoos, public aquaria).

The agent according to the invention is made available in the form of individual component products or a multiple component product, e.g. as packing for 100 to 1000 1 of maintenance system, preferably as aqueous concentrate. The individual components to in the concentrate can hereby be combined in the amounts corresponding to the previously mentioned dosage recommendations. However, the individual components can also be packed individually or in compatible mixture in the single dose corresponding to the dosage amount or in larger amounts in solid form, e.g. as powder, granulates, extrudates, pearls, capsules or in tablet or liquid form. In this form, the individual partial problems can be solved individually or in any desired combination by addition of individual components or mixtures. Exact statements about the dosing of the concentrate individual components or mixtures are to be found in the packaging or on the leaflet in the packaging.

The dosing frequency is given from the functional use. It extends from daily over every two days and once or twice a week to once per two weeks or according to need.

Additional treatments in the case of use of the products according to the invention: Since, in the case of the described mostly oxidative breakdown processes, the amount of oxygen necessary for the complete breakdown is used up, expediently, besides the use of the water treatment agent according to the invention, an additional treatment is carried out. Thus, it can be necessary since the oxygen of the maintenance water standing in equilibrium with the atmosphere is limited to about 8 10 mg/l (15 25 0 C) to, introduce oxygen during the water treatment in order not to bring about an 02 deficiency situation.

By means of permanent mild fine-bubble aeration or addition of an amount of hydrogen peroxide equivalent to the 02 requirement, the described water treatment is also oxygenneutral and thus environmentally neutral.

Claims (18)

1. Process for improvement of the water quality of biological maintenance systems, said method including the step of adding to the maintenance system individually or in any desired combination a) for the lowering of the phosphate concentration, at least one easily or sparingly soluble A13+, Fe 3 TiO 2 ZrO 2 or Ca 2 salt of an organic carboxylic acid, possibly in admixture with an organic carboxylic acid; b) for the lowering of the nitrate concentration or limitation of the nitrate increase, at least one water-soluble N-free, biologically decomposable organic compound; c) for the increasing of the carbonate hardness or of the HCO 3 concentration, at least one alkali metal or alkaline earth metal salt of a carboxylic acid; d) for the increasing of the total hardness or of the concentration of Ca 2 and Mg 2 hydrogen carbonate, a mixture of at least one Ca 2 and Mg 2 salt of an organic carboxylic S 15 acid; and e) for the increasing of the C02 concentration, at leat one biologically decomposable compound.

2. Process according to claim 1, wherein for the lowering of the phosphate .20 concentration, an Al 3 Fe 3 TiO 2 ZrO 2 and/or Ca 2 acetate, formate, tartrate and/or especially citrate is added.

3. Process according to claim 1 or 2, wherein 1 to 100, preferably 10 to mg/1 aluminium and/or iron (III) citrate is added weekly or fortnightly.

4. Process according to claim 1, wherein for the lowering of the nitrate concentration or limiting of the nitrate increase, one adds at least one aliphatic compound, e.g. an alcohol, a sugar or a carboxylic acid.

5. Process according to claim 4, wherein glycerol, sorbitol or ethanol, a pentose, a hexose or saccharose or acetic, citric, tartaric or lactic acid is added.

6. Process according to claim 4, wherein a mixture of citric or acetic acid and saccharose or especially a mixture of citric acid, tartaric acid and saccharose is added. 24/03/05,ehl2574 -26-

7. Process according to any one of claims 4 to 6, wherein every second day or three times weekly 5 to 100, preferably 5 to 40 mg/1 of the compound or the mixture is added.

8. Process according to claim 1, wherein for the increasing of the carbonate hardness or of the HCO 3 concentration, at least one alkali metal or alkaline earth metal salt of an aliphatic carboxylic acid is added.

9. Process according to claim 8, wherein an alkali metal or alkaline earth metal salt of citric, acetic, lactic, tartaric, formic, propionic or malic acid is added.

Process according to claim 8, wherein alkali metal and/or alkaline earth metal salt is added so much and so often that the desired carbonate hardness is achieved and remains maintained.

11. Process according to claim 1, wherein for increasing of the total hardness or of the concentration of Ca 2 and Mg 2 hydrogen carbonates, a mixture of Ca 2 and Mg 2 salts of organic carboxylic acids is added.

12. Process according to claim 11, wherein for the desired control of the composition of the total hardness, further Ca 2 and Mg 2 chloride and/or sulphate is added. *oo i*

13. Process according to claim 1, wherein for increasing of the CO 2 25 concentration, a carboxylic acid and/or an alcohol and/or a sugar is added daily or every two days.

14. Process according to claim 13, wherein glycerol, sorbitol or ethanol, a pentose, a hexose or saccharose or acetic, citric or lactic acid is added.

Process according to any one of claims 13 or 14, wherein 1 to preferably 3 to 10 mg/1 is added daily or every two days 2 to 40, preferably 6 to 20 mg/1 of the biologically decomposable compound or a mixture of such compounds is added. 24/03/05,ch12574.spc.26 -27-

16. Process according to claim 1, wherein an amount of oxygen or hydrogen peroxide equivalent to the 02 requirement of the maintenance system is introduced.

17. Single or multiple component product for the improvement of water quality of biological maintenance systems for the functional, causal use according to need, containing (singly or in combination) 1) at least one easily or sparingly soluble A13, Fe 3 TiO 2 ZrO 2 or Ca2+ salt of an organic carboxylic acid, possibly in admixture with an organic carboxylic acid; at least one water-soluble, N-free biologically decomposable organic compound; 3) at least one alkali metal or alkaline earth metal salt of an organic carboxylic acid; and 4) a mixture of at least one Mg 2 and Ca 2 salt of an organic carboxylic acid.

18. Single or monocomponent product according to claim 17, containing singly or in 15 combination 1) an Al 3 Fe 3 TiO 2 ZrO 2 and/or Ca 2 acetate, formate, tartrate and/or especially citrate; 2) glycerol, sorbitol or ethanol, a pentose, a hexose or saccharose or acetic, citric, tartaric or lactic acid; i: 20 3) an alkali metal or alkaline earth metal salt of citric, acetic, lactic, tartaric, formic, propionic or malic acid; and 4) a Ca 2 or Mg 2 salt or a mixture of Ca 2 and Mg 2 salts of organic carboxylic acids, possibly in admixture with Ca 2 and Mg 2 chlorides and/or sulphates. o. S25 Dated this 2 4 th day of March, 2005 TETRA GMBH By Their Patent Attorneys CALLINAN LAWRIE Xjl Ml.MW 24/03/05,ch 12574.spc27