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Discussion Starter · #1 ·
I'm just curious, In my 150, Iv'e set my ph control below 6.5 and c02 runs almost constantly.

At what point does the ph stop dropping?

I have no disturbance on top of the water, a power head is mid/upper level of tank.

There is a skimmer and two cansister filters moving water, thats about it.

There are two pieces of bog wood and medium plants growing.

Substrate : Black florite / eco-complete
Temp 82
Ph bubble is green
Kh= 2
Ph= 6.5
Nh3= 0
N02= 0

Ferts are
Kno3, K2so4, Kh2po4 and trace csm+b, dosed every other day , along with Excel

If I were to allow the c02 to run continuously would it lower? In not, then why? without adding buffers to lower it.

I'm not attempting to lower past 6.5, just curious, for a piece of mind as to why it stays the same , and if the ferts affect the ph in any way.

Just trying to educate myself

21,012 Posts
It really makes no difference what the pH is. The CO2 will run continuously if you have a low bubble rate, but not continuous if you have a high bubble rate. I think you should first disconnect the controller, then adjust the bubble rate until you get good pearling, but no distressed fish. Then use the controller to read the pH, and use that value when you set the controller to control the CO2. If you also increase the bubble rate a bit, once the controller is controlling the CO2, it will allow the CO2 concentration to build up much faster when it first comes on.

It would do a lot of good to have the water surface rippled from flow just under the surface. Don't make it ripple so much you get splashing, but the whole surface should have some rippling. That increases the surface area of the water, so you get more oxygen into the water, and that allows the fish to be able to handle the higher CO2 level much more easily. It "wastes" a little more CO2 that way, but CO2 is cheap.

Super Moderator
12,113 Posts
I would assume the solenoid would turn off your CO2 when the pH drops below the set point. If the CO2 is continuing to go all the time, either the solenoid is not turning off the CO2 properly, or you just have not reached the lower set limit for the pH.

As a side note, hopefully you are using a 4 dkH reference solution in your drop checker.

Since you are injecting CO2, Excel is also not required.

Fertilizers do not affect the pH in any significant way.
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