# Decreasing pH and hardness



## idris (17 Apr 2013)

I'm vaguely thinking about trying to reduce the pH and hardness of water in my tank so I can keep fish that prefer softer, more acidic water. It's a while since I read up on this sort of thing, but from what I remember I could use peat to simultaneously reduce pH and hardness.

I think my best option for doing this is by using a bag (or stocking) of aquatic peat in the filter.

Have I remembered this correctly, and are there any other considerations, like speed of such changes in water chemistry, or the effects on established plants and/or existing livestock?


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## NanoJames (17 Apr 2013)

I think some shops do peat balls that are measured to give you the right amount of peat for a certain amount of water. Bearing in mind that peat will cause a black water effect, but I think amazon fish quite like that! There are also comercial PH products that can make it go up or down but these might not be sufficient. Hope this helps!


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## Ed Seeley (17 Apr 2013)

Peat has a negligible effect on pH and hardness unless your tap water is fairly soft already.  IME the only way to reliably lower the pH and hardness in a plant and fish friendly way is to use water with a lower GH and KH - ie. RO water.


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## BIN578 (17 Apr 2013)

I agree with Ed.  Trust me I have asked this question many times and it all boils down to RO.


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## lurch1000 (17 Apr 2013)

What is your pH, GH and KH? Be helpful to know before settling on or dismissing any ideas.


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## mafoo (18 Apr 2013)

RO is the only way. But bear in mind that RO is neutral until it has something disolved in it to change the pH. So if you add RO to alkaline water your still going to have alkaline water. If your using CO2 that will help lower the pH a bit but once you add the RO you will have to have something in there to lower the pH - like a peat ball or specific minieral salts or one of the pH down products.


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## George Farmer (18 Apr 2013)

RO + soil substrate (Aqua Soil, NutraSoil etc.) is probably the most effective way to achieve soft and acidic water with a stable pH. There's a reason keepers and breeders of delicate softwater fish and shrimp swear by it.

Using any products in an attempt to soften/acidify mineral-rich water is futile, with the exception of using a soil substrate.


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## idris (18 Apr 2013)

I haven't tested the water recently and my test kit is probably past it's use-by date by now. The pH used to be about 7.4: I can't remember what GH and KH were I'm afraid, but I know they were relatively high. (We live in a chalk stream area.)

I've looked at RO before but, for various reasons, of that's the only option I'll probably not bother. 

Peat as a substrate isn't an easy option either as it will mean a complete overhaul of an awkwardly deep and 'scaped tank. (Not something I have the time or energy for.) I could  replace a little of my Adakama without too much hassle, but probably only about a litre (in a 250l tank).

George - Is there any reason why something like Aquasoil in the filter wouldn't work?


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## George Farmer (18 Apr 2013)

> George - Is there any reason why something like Aquasoil in the filter wouldn't work?


The soil would likely soon break down and cause excessive clouding.


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## George Farmer (18 Apr 2013)

What fish are you wanting to keep? Most captive bred species are ok in harder water.


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## Martin Osmond (18 Apr 2013)

Silly question but does it make any difference to plants?


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## tubamanandy (18 Apr 2013)

Would pre-filtering the water with de-ionising resin not be a more cost effective solution ?


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## idris (18 Apr 2013)

George - Fair point on soil break down. 
I want to get some Killifish. The cognocenti seem to think they need soft, acidic water, but I don't know how neccessary that really is. 

Tubamanandy - I was under the impression that de-ionising filters just replaced one sort of salts with another sort. Or am I thinking of something else?


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## tubamanandy (18 Apr 2013)

All I know is I dont have particularly hard water but at certain times of the year, I pre-filter my water through a simple pod filled with de-ionising resin and the TDS drops very significantly (RO water would clearly be better)


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## ian_m (18 Apr 2013)

idris said:


> Tubamanandy - I was under the impression that de-ionising filters just replaced one sort of salts with another sort. Or am I thinking of something else?


Correct, usually use to remove the left over trace calcium ions from RO membrane with either sodium or potassium ions. Unless you have a whole house water softener which replaces all the hard calcium with soft sodium, but then no good for fish.


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## idris (18 Apr 2013)

Deleted.


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## tubamanandy (18 Apr 2013)

I was just on about the mixed bed de-ionising resins - not a particular one to remove eg. Nitrate


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## idris (18 Apr 2013)

Ah yes. Stupid question!


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