Safely Lowering Ph

Royston · May 27, 2013

My ph is above 8 in my freshwater 500ltr tank, how can I keep it reduced for my co2 .... Is R O the answer ,if so can I do half r o and half tap water to keep in minerals and the ph to 7.5 approximate ?

eaglesaquarium · May 27, 2013

That would work, if you're willing to go to that expense.

I don't understand what you mean when you say, "how can I keep it reduced for my co2?".

cornclose · May 27, 2013

Adding CO2 will reduce the pH. How quickly and by how much will depend on your buffering capacity (KH).

Royston · May 27, 2013

My k h is 11 and ph 8 so the co2 doesn't do any thing. It's been running for 3 weeks now and ph only goes down a bit when I have it on :-(

.. I have seen R O units for around £70

eaglesaquarium · May 27, 2013

Why do you want to lower the pH is my real question? The CO2 is still there...

cornclose · May 27, 2013

How much did your pH go down by ? And what type of CO2 diffuser/reactor are you using ?

Royston · May 27, 2013

The ph only goes down a small amount and the reactor is the JBL that came with the 602 kit.
Going by the chart my ph and K H needs to be in the green .. I have the JBL permanent co2/ph checker in the tank and it has never read above 3ppm, so if I reduced the ph/kh the co2 work and get up to 30 ppm. (I am Most probably completely wrong)

cornclose · May 27, 2013

I would suggest then that either the CO2 you're injecting isn't dissolving into the water (i.e. it's being wasted, perhaps a leak ?) or your pH and/or KH measurements are inaccurate.

Reducing the pH of your water by means other than CO2 injection won't then allow you to inject CO2 more easily. One of the other two (above) would be first to check..

Royston · May 27, 2013

The co2 is getting into the tank at the rate of 3 bubbles per second which I thought is quite high, I'm waiting for a inline defuser that I ordered to hopefully do a better job of dissolving the co2.
The ph test is api and using the seneye and kh is a JBL one
Going by the chart the ph and kh are the influencing factor of how much co2 you need to inject to get the ideal amount.

cornclose · May 27, 2013

Out of interest, how closely do your API pH test and seneye readings correlate ?

Your three bubbles per second doesn't sound too far off, but if you're losing two bubbles per second thats not being dissolved into the water then it won't be anywhere near enough.

Royston · May 27, 2013

The seneye and api seem accurate with each other.
I will wait for the inline defuser to be delivered (from Hong Kong ) and see if that does a better job than the JBL reactor as its meant to diffuse 90%+ before I go down the R O route.. But the co2 would still need to knock the ph down a fair bit to get me in the green.

cornclose · May 27, 2013

I use one of these CO2 inline reactors:

It's the best reactor by far I've ever used, and I've tried most. There is absolutely NO CO2 wastage from these. Every bubble has to get dissolved into the water and thus into the tank, unless you have a stupidly high bubble rate which empties the water from the reactor!