Weird Ph Increase

[iamwhoiam]

My tapwater in my area is relatively hard, i haven't tested the value... but the kettle needs a good scrubbing every few months to feed my tea habit

Anyways, my tank pH is 8.0 and consistently stays around that point

However, my tapwater pH is 7.2 and my RO water is 6.8. I use a 50/50 mix to help soften my water... but my pH is still 8.0 for some reason?!?!

I suspect my gravel... it's white in appearance so it's probably not inert. The packaging doesn't state what it is i don't think (i will check later)... but it looks something like this...

 

[Bignose]

It is not uncommon for water companies to dissolve extra CO2 in their tap water so that mineral build up is lessened. As the plant keepers know, the extra CO2 makes the water more acidiic. Let your tap water sit out for a few hours (agitating it is even better) and then test it. If that water's pH is not near 8.0, then it could be the rocks in your tank.

 

[iamwhoiam]

It is not uncommon for water companies to dissolve extra CO2 in their tap water so that mineral build up is lessened. As the plant keepers know, the extra CO2 makes the water more acidiic. Let your tap water sit out for a few hours (agitating it is even better) and then test it. If that water's pH is not near 8.0, then it could be the rocks in your tank.

Previously I just tested the pH straight from the tap. thanks for the tip... i will try that and post back my results

 

[iamwhoiam]

Well here's what i've come up with:

Tapwater was left to sit for 72 hours and after pH testing... was found to be around 7.8 ... water company must have added CO2 in

RO water (very soft i'd say)... with white gravel in was left to sit for 72 hours... originally tested 6.8 and is now 7.2 ... so the gravel has a small contribution

My solution is just to add a CO2 injection to the system, bringing my pH now to 7.0

Thanks for the advice about the water company's CO2... i'd have never have guessed!

 

[Bignose]

RO water (very soft i'd say)... with white gravel in was left to sit for 72 hours... originally tested 6.8 and is now 7.2 ... so the gravel has a small contribution

I just wanted to point out that the difference of 0.4 pH units is probably well within the errors of the test. The biggest proof of that is RO water should, by definition, have a pH of exactly 7.0. But, with the drops and the reading of the colors off the charts, there is a significant amount of error in the whole process.

Finally, please test your CO2 system in a tank without fish. The fish will be stressed out with fluctuating a pH, and since you have experienced the confusions of the water chemistry firsthand, it would be better for you to perfect your technique without stressing the fish.