Can substrate lower ph too much

[Karen H]

Hi. I am new to keeping a planted tank. It has been running for 4 months now. Some plants have grown well some not. I have nutra soil substrate it says on tub can lower ph to safe level, but my ph is 6.4 . Local fish store tested water to confirm my tests everything else ok apart from ph and kh0. Help could thie be substrate or something else . Had 2 otoclinclus die over night after 6 weeks in tank thought I could see fin rot on 1.
Ideas please

 

[Alastair]

Hi Karen
Is your ph now 6.4 or 6.4 from the tap. Some or most fish shops still think that a ph below 7 isnt right. I use tmc nutrasoil and my ph is currently 6.2 and kh 0 and have had no fatalities. I also keep ottocinclus

 

[Karen H]

Hi Alastair , thanks . I will leave alone and see what happens. Don't know what to put deaths down too.

 

[Karen H]

Hi Alastair . Meant to add ph 6.4 in tank. Tap is ph 7.2. Did water change will test later today

 

[Alastair]

Hi Alastair . Meant to add ph 6.4 in tank. Tap is ph 7.2. Did water change will test later today

Nothing wrong with a ph of 6.4