# Precipitation of fertilisers due to hard water.



## Sarpijk (14 Jul 2015)

Every summer around June my aquarium goes downhill. After reading the thread about EI I started wondering whether the increased water hardness makes my dosing less adequate.

The reason this happens during the summer months is because I employ two pc fans in order to keep the temperatures low. As a result a lot of water evaporates which I replenish using dechlorinated tap water thus increasing general water hardness.

Should I invest in an RO unit in order to have water to add during top-offs?


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## dw1305 (14 Jul 2015)

Hi all,





Sarpijk said:


> As a result a lot of water evaporates which I replenish using dechlorinated tap water thus increasing general water hardness. Should I invest in an RO unit in order to have water to add during top-offs?


 You are right, the conductivity and hardness of the water will continually rise as salts are added (from the tap "water") and H2O evaporates. 

RO is an option. Rain-water may be another? depending upon your circumstances.





Sarpijk said:


> Every summer around June my aquarium goes downhill


 It might be a temperature issue, rather than a nutrient one. Gases are less soluble at higher temperatures, and some plants grow less well.

cheers Darrel


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## Sarpijk (14 Jul 2015)

Cheers Darrel, as I have mentioned I use two PC fans connected to a temperature controller. I keep the temperature at 27 Celsius max. I have kept the same fertilizing regimen, co2 is stable so the only thing that I can think of is the increased hardness due to daily top offs. 

I have recently started  increasing my daily dose of ferts to see if it makes a difference. Rain-water is not an option. If I use some peat in order to soften tap water before I use it for top offs is it going to be the same as adding RO water?

Final question: Is it just the  micros that are influenced by hard water or does the same happen to macro nutrients as well?


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## Rahms (14 Jul 2015)

how big is the tank?

doing more frequent (non-RO) water changes will keep hardness closer to your tapwater, but obviously that's no use if its not feasible!


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## dw1305 (15 Jul 2015)

Hi all,





Sarpijk said:


> If I use some peat in order to soften tap water before I use it for top offs is it going to be the same as adding RO water?


Not really, theoretically peat will have some softening effect, via ion exchange, (the exchange sites are initially filled with H+ ions, which will be swapped for multivalent Ca++ ions etc.), but in practice you need a lot of sphagnum peat to treat a relatively small volume of very hard water. 





Sarpijk said:


> Final question: Is it just the micros that are influenced by hard water or does the same happen to macro nutrients as well?


It will effect phosphorus (P) availability, as well as iron (Fe) and potentially magnesium (Mg). 





Rahms said:


> doing more frequent (non-RO) water changes will keep hardness closer to your tapwater, but obviously that's no use if its not feasible!


Is an option.

cheers Darrel


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## parotet (15 Jul 2015)

If your tank is small (under 65 liters) and you only want the RO water for topping (and maybe for watering orchids, mosses or sensitive plants) it is not worth to invest in a RO unit. Buy it, it's just 0.1€/liter, even free if you are a good customer of your LFS. Note that for an optimum RO unit use you need to have really good pressure (otherwise it is not efficient at all) and that in hard water areas you need to replace the cartridges (is this the name in English?) at least once a year... Not cheap unless you produce a lot of water.

Jordi


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## Jose (15 Jul 2015)

If you think there are precipitation issues then you can just dose a half more in summer. This is easier than making RO water. Still, you cant be sure its the hardness of the water even if temp goes up by just a couple of degrees plants metabolism is going to go up by a lot and you need to keep up with their needs ferts and co2-wise..


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## Marcel G (15 Jul 2015)

Jose said:


> If you think there are precipitation issues then you can just dose a half more in summer. This is easier than making RO water. Still, you cant be sure its the hardness of the water even if temp goes up by just a couple of degrees plants metabolism is going to go up by a lot and you need to keep up with their needs ferts and co2-wise..


By increasing the temperature just by couple of degrees (say +5°C) you will hardly notice any difference in metabolism (growth) rate. Also, if iron precipitates in hard water, then adding more iron won't do any better (won't solve the problem). The only result will be more iron precipitates. The solution may be to use some stronger Fe-chelate (like Fe-DTPA) or to reduce the hardness (use soft water).


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## Jose (15 Jul 2015)

ardjuna said:


> By increasing the temperature just by couple of degrees (say +5°C) you will hardly notice any difference in metabolism (growth) rate. Also, if iron precipitates in hard water, then adding more iron won't do any better (won't solve the problem). The only result will be more iron precipitates. The solution may be to use some stronger Fe-chelate (like Fe-DTPA) or to reduce the hardness (use soft water).


I use Fe-EDTA in 18 dKH or so water and Ive never had low iron deficiencies, simply because I dose a lot. Remember not all reactions have a constant of 1 so some of them might take place only to a certain degree. So all the iron does not precipitate in a few hours. If it did how do you explain I dont get these type of defficiencies with medium-high light and I get great growth which as far as I can tell only changes with co2.


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## Jose (15 Jul 2015)

ardjuna said:


> By increasing the temperature just by couple of degrees (say +5°C) you will hardly notice any difference in metabolism (growth) rate.


Again this depends if plants are being limitted by temperature or not.


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## Sarpijk (15 Jul 2015)

Thanks for the input guys. Well my tank is 60 litres so I do not need a lot of RO water, about 5 litres a week I'd say. I have already spoken to my LFS and I will be able to get some water from them so thanks for the suggestion Jordi.

Some questions:

Would boiling my tap water and letting it cool, help in reducing the hardness? Whenever I boil water there is always some calcium deposits on the walls of the pot.

For how long can I keep RO water stored in a sealed container?

Finally, I have just realised that whenever I add Seachem Iron my water goes cloudy. Is this a sign of precipitation rendering my dosage ineffective?


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## Marcel G (15 Jul 2015)

Sarpijk said:


> whenever I add Seachem Iron my water goes cloudy. Is this a sign of precipitation rendering my dosage ineffective?


Yes, the cloudiness is the result of iron precipitation. Once the iron precipitates it is not available to plants anymore. Plants are able to "transform" it back into available form, but this can happen only in the root zone, and only in very small amounts when the plants are really iron deficient.
The plants don't invest their energy into this kind of iron uptake when they are not on the brink of death.


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## Sarpijk (15 Jul 2015)

No wonder why my reds are not that red! The EI thread was an eye opener for me!


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## dw1305 (15 Jul 2015)

Hi all,





Sarpijk said:


> Would boiling my tap water and letting it cool, help in reducing the hardness? Whenever I boil water there is always some calcium deposits on the walls of the pot.


Yes, but you need to pour the water out of the kettle when it has just boiled.

Because (bi)carbonates are in equilibrium with CO2, and gases are less soluble at higher temperatures, when the water boils all the gas comes out of solution, and this means that all the HCO3- does as well.

Calcium carbonate (CaCO3) is likely to be the least soluble carbonate, and CaCO3 ("limescale") is deposited.

If you let the water cool in the kettle as it cools down atmospheric CO2 will diffuse back into the water, and the precipitated CaCO3 will go back into solution as Ca++ and 2HCO3- ions.

You will need to strain the boiled water through a fine mesh as well to get any particulate CaCO3.





Sarpijk said:


> For how long can I keep RO water stored in a sealed container?


Several billion years, but you need a food grade storage container.





Sarpijk said:


> Finally, I have just realised that whenever I add Seachem Iron my water goes cloudy. Is this a sign of precipitation rendering my dosage ineffective?


 Yes.

It isn't a product I've use, but I think the iron source is "ferrous iron (Fe+2) gluconate". Have a look at this thread <"Chelated Fe">.

cheers Darrel


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## parotet (15 Jul 2015)

I can store rainwater in 25 liters plastic containers but I found that the water smells better (not sure if this has any consequence on the quality) if I leave the container cap opened (of course in a dark place)

Jordi


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## Marcel G (15 Jul 2015)

dw1305 said:


> I think the iron source is "ferrous iron (Fe+2) gluconate".


In Seachem products there is definitely Fe-gluconate (and the iron is there in the Fe+2 form). The problem is that the gluconate is very weak chelate (in fact, it's not even a true chelate, it's an organic complex), and even Seachem admits that the Fe-gluconate won't last more than 1 day in our tanks. Also when you use it in hard/alkaline water or if you supply it in high amounts, the reaction is even faster, so in such a case the iron will be available for plants for even shorter period. I would say that Fe-gluconate is not optimal source of iron for plants under standard conditions. If I was to use it I would combine it with other Fe-chelates (like Fe-DTPA). It's always a good idea to use several Fe-chelates. Fe-gluconate seems to be the easiest complex for plants to uptake (due to Fe+2 ions it contains), but Fe-DTPA will be available for plants for much longer period so it's much better long-term source of iron.


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## Andy Thurston (15 Jul 2015)

dw1305 said:


> It might be a temperature issue, rather than a nutrient one. Gases are less soluble at higher temperatures, and some plants grow less well.





Sarpijk said:


> I keep the temperature at 27


I'd try reduce the temp a degree or two unless you have fish that need the higher temp. if that doesnt work then look into nutrients


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## Sarpijk (15 Jul 2015)

I could possibly reduce the temperature but during the Greek summer this would mean a huge amount of evaporation. I do not want to deal with that. The temperature outdoors reaches 35 celcious so maintaining a temperature below 27 sounds unrealistic. Unfortunately I work long hours away from home and I cannot leave  the a/c on.


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## parotet (15 Jul 2015)

It's the same for me in Spain, there's no way to keep my tanks under 27*C during the summer, even using fans,  a/c or whatever. I just assume it's the bad season... But every cloud has a silver lining and I can keep my tanks between 20 and 24C during 9 months without using heaters.
The only thing I am doing is increasing the frequency WCs and it keeps the tanks in shape 

Jordi


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## dw1305 (15 Jul 2015)

Hi all,





ardjuna said:


> Fe-gluconate seems to be the easiest complex for plants to uptake (due to Fe+2 ions it contains), but Fe-DTPA will be available for plants for much longer period so it's much better long-term source of iron.


I think Fe-DTPA is better option as well. I also think the ferrous (Fe++) iron will become ferric (Fe+++) pretty much <"straight away in use">.

cheers Darrel


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