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Help with Aquasoil PH

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Hi all,


I have setup a new 10gal tank for bee shrimp

I have added almost a full 9L bag, to around 8 cm thick substrate. With the addition of old sea mud and bacter 100 as first layer, filled with 3cm aquasoil and some more bacter 100 and filled to desired level with aquasoil. 


Our tap water has a Ph of 8 and KH of 4


I have done 3 90% w/c in the last 3 days using tap water and adding prime for chloramines.

The tanks p/m is at 0 KH and 7 PH. isn't the PH supposed to be less?

The tank is running on a canister of 400L/h and airstone for oxygen for the filter bacteria at 24 Celcius.

I have also setup a small tub as a experiment with tap water and aqua soil, around half/half and the PH of this is at 6.2/6.4

I will run the cycle for 4 weeks and change over to SS GH+ and RO/DI water


So the question I have, is the PH staying at 7 due to the tap water PH of 8?

And, when completing the cycle and changing to RO with PH 7, will it drop lower then to say PH 6.5 or whatever?


any advise or recomedation would be great


Picture of the tank



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Hello Maurice,

Yes I agree with you that the ph should be a lot lower. Considering you have 8 cm of soil I am very surprised it is not lower then 7ph.

One thing that sticks out for me is that your KH is 4 which would restrict ph movement but it does not seem too high. If you can change over to RO water now I would give it a try. Maybe there is something in your tap water that is countering the buffering soil.

Also what are you using to test the PH?

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I think it's because your tank has not completed cycling yet.

When the tank gets close to cycling, your pH will drop. Once those bacteria starts breaking down nitrogenous waste, you will see pH drop. 

<edit> quick chemistry lesson

pH measure of the relative amount of free hydrogen (H) and hydroxyl ions in the water.

Ammonia = NH3

When cycling starts in a tank, bacteria convert NH3 to Nitirite.

Nitrite = NO2.

See how the hydrogen H has been reduced? NH3 vs NO2?

Now that the tank water has less Hydrogen H overall, pH drops !



pH 7 is perfect for cycling a tank. (well except of pH8 or higher).

24degC is too cold for cycling a tank fast. You have no shrimp in the tank yet, so turn the heat up to 27 or 28. After cycling, turn the heat back down before adding shrimp.


Stop all those water changes this early in the cycle.

You only need to do water changes when the pH looks like it is getting too low (say 6.0 - 6.4). At low pH the bacteria goes dormant and the cycle stalls (or slows). A water change at this time should get things going again. Keep monitoring pH. Repeat if it drops again, until Ammonia & nitrite are zero.


Just be careful after cycling. With 8cm of substrate, your pH is going to drop VERY low!

Edited by jayc
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