Why Ph Is So High?

[nerijusa]

I have quite high PH in my aquarium. It is 7.5 (KH-4, GH-6, CO2 1 buble/second). I am doing weekly water changes (using RO water with PH around 6.80), but despite that PH is still high (it diminishes to 7.2 after water change but it increases again after a few days). When I cut off my CO2, PH in aquarium has risen to 8.50. Maybe can help me to indentify the source of high PH? What methods could be to decrease it (I do not want to use chemicals)? I have had some fishes losts, maybe it is because of not stable PH. Thanks in advance.

 

[Tommy Gunnz]

7.5 is not a high Ph and you are right, you should avoid big swings in Ph to avoid shocking your fish.

I am not the plant expert, but I do know that CO2 has an impact on Ph and apparently it lowers it in your case.

What is your substrate?

What is the Ph of your water before you put it in the tank (from your sink or tap)?

What fish are you keeping?

How do you clean your tank? Are you sure to remove all of the dead, decaying plant matter and any food that slipped past your fish?

How do you feed your fish?


There are really quite a few reasons for high Ph as well as low Ph. Most usually, it is not hard to keep a Ph stable in a non-planted tank and so I am leaning towards the CO2 injections or plants as being the source but I haven't the experience with them to know for absolute sure.

 

[zoekin8yg]

If you have any rocks in there they could be causing a problem!

 

[Tommy Gunnz]

Ture, calcium based rocks or gravel like crushed coral will raise Ph and I have heard that some river rocks will lower Ph. Not exactly a geologist though. Good test for rocks that wont change Ph is the vinegar test for more people.

Still think it is the CO2 though.

 

[nerijusa]

Ture, calcium based rocks or gravel like crushed coral will raise Ph and I have heard that some river rocks will lower Ph. Not exactly a geologist though. Good test for rocks that wont change Ph is the vinegar test for more people.

Still think it is the CO2 though.

Thanks for some hints. My aquarium is well planted (that is a reason why I am adding CO2). I have 2 wooden rocks inside (which have to lower PH). I am cleaning aquarium once a week (20-25 percent water change using RO water). I have problem with algues, they flourish...(but I hope they do not influence my PH). Maybe gravel is the reason for high PH?

Where can I find more information about vinegar test?

 

[fishcollector7000]

i have a high ph also. what kind of river rocks help lower ph? i have never heard this before but sounds interesting! and i may try it! do plants increase ph then?

 

[Squid]

i have a high ph also. what kind of river rocks help lower ph? i have never heard this before but sounds interesting! and i may try it! do plants increase ph then?

Bogwood has lowered my PH... and i dont even want it to.

Squid

 

[Glod]

The vinegar test is simply take the rock from the tank. Add a generous splash of vinegar to the rock and see if there is any kind of reaction. Bubbles will indicate that the rock is probably buffering your PH upwards (calcium or similar in the rock). If that's the case, don't use the rock in your tank if you want your PH to be lower.

CO2 generally reduces the PH as does bogwood (real wood) so I doubt they are the problem. If your rocks are petrified wood it's possible they are the cause.

 

[George Farmer]

Substrate or rocks. They may contain lime. Lime = higher pH (and KH)

Just so you know, CO2 lowers pH. Plants can raise pH due to CO2 consumption, not by much though.

Bogwood lowers pH. No rocks will lower pH.

Test your tap KH and tank KH. I expect your tank will be higher. KH influences pH.

Pea gravel contains lime.