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How to decrease pH?

Mil

New Member
Hello everyone!

I have been testing my pH recently and it seems to be consistently at around 7-7.5, but ideally i would like it to be lower as i have Apistos in two separate tanks which i would love to get spawning.

I have added in so many almond tree leaves constantly over the past few months, they turn the water into a nice light tea colour, but the pH out the tap is around 7.5 and with the weekly water changes i do it seems to be having no affect.

I recently found out about alder cones so i have ordered a box of them and will be adding them this week.

Can anyone help with how to use rainwater, i have a communal garden where there is a tank that collects rainwater and i have access to that, but not sure if i need to treat the water first or not.

I hear peat help, but I'm not sure what sort (is it just garden peat?) and how i go about adding this into the tank too.

Any help is greatly appreciated!

Thanks. Mil
 

Linus_Cello

Active Member
5 Year Member
What decorations do you have in your tank? Maybe you are using certain rocks that are buffering the pH?
 

Mike Wise

Moderator
Staff member
5 Year Member
When I used rainwater I always waited about 15 minutes before actually collecting water. This allowed the roof to be flushed of any debris and pollutants first. Since you don't have this option with a communal collection site, it probably would be best to run the water through a particulate filter and then filter it with some high-grade activated carbon. Something like a power box filter comes to mind.
 

Mil

New Member
What decorations do you have in your tank? Maybe you are using certain rocks that are buffering the pH?
In the larger tank I have a few large 'dragon' stone in there about 3kg worth, but was told this is pH neutral and also doesn't contribute to hardness (unless i am mistaken), and a large piece of driftwood too. Other than that there are only live plants. The smaller tank only has a stone about the size of a matchbox in it though and the pH of the two tanks are very similar.
 

Mil

New Member
When I used rainwater I always waited about 15 minutes before actually collecting water. This allowed the roof to be flushed of any debris and pollutants first. Since you don't have this option with a communal collection site, it probably would be best to run the water through a particulate filter and then filter it with some high-grade activated carbon. Something like a power box filter comes to mind.
The water actually goes through a roof top grassy meadow thing, so i assume it kind of gets filtered as the water is crystal clear. But i get that there might be some contaminants in the water i cant see so i will try this, thanks Mike.
 

dw1305

Well-Known Member
5 Year Member
Hi all,
The water actually goes through a roof top grassy meadow thing, so i assume it kind of gets filtered as the water is crystal clear.
It will probably pick up some bases from the media the green roof is growing in.
Honestly I wouldnt use rainwater in the London area
I wouldn't worry too much, there isn't much heavy industry now and it is a smoke free zone, you can always use the Daphnia bioassay.

You live in London, so you are likely to have hard water from the tap. Because of the level of carbonate buffering in the water you can''t really lower the pH with peat etc.

cheers Darrel
 

dw1305

Well-Known Member
5 Year Member
Hi all,
But there are so many other ways to do ...like with hydrocloric acid for example.
That is a method you can use, the pH will fall because the addition of H+ ions will have converted the temporary (dKH) carbonate hardness to CO2, which out-gases. It doesn't change the permanent hardness (dGH), because you just get CaCl2 formed. Calcium chloride is highly soluble, so you have Ca++ and 2Cl- ions in solution.

CaCO3+ HCl -> CaCl2 + CO2 + H2O

Personally I'm not convinced that there is very much advantage in acid-softened hard water over hard water. You haven't changed the amount of cations, or the conductivity, just the pH.

cheers Darrel
 

Mil

New Member
I’m not sure I’m confident enough to start dosing HCl acid.
I’ve collected about 10l of rainwater and used an old filter to turn it over some carbon for a few hours and added that to the 125l tank. % wise it’s not a lot but will slowly keep doing this every few days to see if it helps.
Alder cones have also been added this evening.
Fingers crossed!
 

themountain

Active Member
5 Year Member
Personally I'm not convinced that there is very much advantage in acid-softened hard water over hard water. You haven't changed the amount of cations, or the conductivity, just the pH.
l
Certainly right but for every ° KH consumed by hydrochloric acid, the conductivity increases by approx. 11 μS / cm
and per half of the KH the pH decreases by 0.3 units..so the you have to do the math to the water you have . There is probably no way around a cation/anion exchanger when your water is that hard.
 

themountain

Active Member
5 Year Member
I’m not sure I’m confident enough to start dosing HCl acid.
I’ve collected about 10l of rainwater and used an old filter to turn it over some carbon for a few hours and added that to the 125l tank. % wise it’s not a lot but will slowly keep doing this every few days to see if it helps.
Alder cones have also been added this evening.
Fingers crossed!
You could buy some purified water and mix it in when you do waterchange...125l doesnt sound so complicated to deal with. How hard is your tap water anyway?
 

Jon Webb

New Member
I have hard water here in the southern desert of New Mexico. Very hard, with high carbonates. I dilute the tap water 1:1 with r/o or distilled water. I also use Fluval peat granules in the filter, and found it doesn’t take much- perhaps 1/2” in a nylon net in a small canister. You can see the tea stain, and if it gets too dark, I add a 25% water change (the 1:1 mix) to my regular routine of a weekly 25% water change. The growth of my plants, the health of my fish and snails, to include fry production, lead me to believe that my tea stained water at pH 6.8 is effective. When I scale up to a 75 gallon tank for Discus, a school of tetras, and some corys, I’ll be adding a few Apistos, and hope to report some fry, as I’ve had with Discus in the past. I’ll let you know, and good luck with your city water. By the way, I am a biochemist, but what we do with aquaria is gardening, an art, and doing too much technical tweaking undermines the stability of a balanced environment in our little gardens. Follow pH, and watch the plants and animals closely. And buy tank-bred livestock.
 
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