best way to maintain PH with a reactor??

[mark]

Looking good now so would say if your reactor is keeping the Ca and alk levels where you want, don't worry about the pH.

On mine find even with a reactor the pH is fairly steady around 8.1 but have macro fuge lit 24/7.

[whatcaneyedo]

I range between 7.9-8.1 right now. To keep my pH up I:

Run a Kalkreactor in addition to my Ca Reactor
Draw my skimmers air from outside the house
Grow macroalgae on reverse lighting
Have a lot of open surface area for gas exchange in my system
Try to keep my Alkalinity in the high range
Use an oversize becket skimmer
Live alone most of the time
Own a lot of house plants
Added DIY second stage to Ca Reactor

[untamed]

I've managed to get my pH to bounce daily between 8.15 and 8.0, even though my Alk is only about 8.

The two-stage Ca reactor runs only during the daylight cycle. Reactor is at pH 6.5, but exits the 2nd stage at more like 7.2.

The Kalk reactor runs only during the night. pH of supplied Kalk is about 12.5.

Refugium lit on opposite cycle to display tank.

BIG skimmer breathing in-house air.

I went after controlling pH in a big way some months back and this is the result. I don't think controlling pH fixed the problems I was having... but I suppose I'm better off for the effort.

[fkshiu]

I have no clue what my pH is at night but I do run a fuge on the reverse light cycle and use kalk in my top off. I also have an exhaust fan sitting right over the tank which probably helps a bit to in evacuating CO2.

My GEO reactor is single chambered.

[christyf5]

Personally I wouldn't worry about it. My tank had that swing for years with no problems, pH is always lower at night anyways.

[steveg]

Hi there, I am thinking about adding kalk to my top up reservoir, would you mind telling me how you are doing it please.

Thanks

Steve

[whatcaneyedo]

If your top off system is gravity fed to a float valve the kalk will constantly plug the float valve so that is not recommended. If your ATO is administered by a pump the kalk will constantly plug up the pump so that is also not a good idea. What you want to do is administer kalk in line with an ATO system incorporating a pump (like the Tunze or JBJ systems) through some sort of reactor or perhaps a simple container. A reactor like the one Precision Marine makes can be purchased or built DIY if you're a little handy. Or a simple container like what Tunze sells could be made out of an empty pop bottle. These inline systems also have the advantage of keeping your top up reservoir clean and limiting the exposure of the kalk solution to CO2.

[Bryan]

Untamed, do you notice a drop in dkh from passing through the second stage?

Originally Posted by untamed

The two-stage Ca reactor runs only during the daylight cycle. Reactor is at pH 6.5, but exits the 2nd stage at more like 7.2.

[untamed]

Originally Posted by Bryan

Untamed, do you notice a drop in dkh from passing through the second stage?

Sorry, I've never attempted to measure that difference. In theory, the dkh should only be HIGHER after the 2nd stage.

The idea, of course, is that the CO2 reacts with the CaCO3. The more the CO2 successfully reacts, the higher the pH goes.

If you stopped the water flow through the reactor...added CO2 until you got to pH6.5...and then stopped CO2 and all flow...then the pH in the reactor would slowly rise back up as the reaction takes place. It wouldn't get all the way to pH 8.0 because the solution in the reactor would become saturated with CaCO3 and higher pH would start to recalcify the CaCO3. (which is what happens when you add too much Kalk too fast).

Since we maintain the first stage at pH of 6.5, any water leaving that stage will be at pH6.5 and therefore contains a LOT of residual CO2. That is unavoidable. That residual CO2 is the problem and drives down the pH of your tank. This is also why you can't flow water too fast through the reactor. Too high a flow rate just blows water and CO2 through the reactor and there isn't enough time for the reaction to take place. That's why slowing the flow rate of your reactor can actually make it deliver MORE Ca/Alk and why larger reactors can deliver more than smaller reactors.

With a multi-stage reactor, that residual CO2 reacts in the 2nd stage and causes the 2nd stage to be higher in pH. CO2 is delivered based on the pH in the first stage, so the 2nd stage is allowed to move higher in pH without causing additional CO2 to be added.

Sorry for the long-winded response!

[Bryan]

Thanks for that, interesting reading. I seem to recall reading the second chamber can cause a slight precipitation of the alk as it passes over the 2nd stage media.