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Re: [APD] CO2 and pH control

Boy are you right about seeing an improvement! Within 2 hours of 
removing the trickle tower, all other variables staying the same, my pH 
has dropped to 7.2 and still going down.  In my enthusiasm to tinker I 
sometimes forget the KISS primciple. Thanks for the reminder. I did 
float about half of the bioballs in the sump just for a cushion for 

You mentioned you like to keep your pH around 6.5-6.6 . Have you found 
that an optimum level?

Yes, I do have my tank inflow valved down to reduce turbulence in the 
tank. I'm not sure what the currant flow rate is but probably 15-20 gph. 
Hopefully now with my standpipe at the tank outflow and sump inflow 
below water level, most of the CO2 that might offgass on the way down to 
the tank will be contained in the piping and reabsorbed.

Now I'll check out your suggestion on the Dupla diffusor. By the way, 
what's your opinion on the use of CO2 resistant air line? I'm using it 
now but will have to buy more to reach from my basement to the tank. And 
yes, I do have a good quality CO2 resistant check valve to protect my 

Thanks again for helping me work through this and find a simple solution.

Gordon Watkins

David Grim wrote:

>Gordon wrote:
>Thanks again for the practical suggestions David. I think I'll start by
>bypassing my trickle tower, an easy change, and see what happens. I'll
>report back on my findings.
>I'm sure you will see improvement doing that. Besides the waster cascading
>down the prefilter plumbing, if you can imagine the increase in surface area
>of the water when it hits and runs over the the bioballs, it must increase
>in surface area tenfold (guess). We use bioballs in CO2 reactors to break up
>and increase the surface area of CO2 bubbles under water for better
>absorption, so if we use them to break up the surface area of water in an
>oxygen rich environment, I would reason that dissolved gasses would leave at
>a faster rate.
>I'm a little reluctant to give up my sump
>entirely as I have an auto evap control system there.
>I'm with you. I am so spoiled by my water changer. Makes it possible to have
>more tanks!
>I would urge you to try an in tank CO2 Diffuser, however. These are not
>expensive. That might be the single most significant improvement in pH
>control you will see if you are keeping your wet/dry as is, even with
>removing the bioballs. The Dupla diffuser puts out pinpoint sized bubbles
>from the getgo, and it is small in size. Only costs about $29.
>Another area of your system you may want to check is how fast is your return
>pump sending water back to the tank? The higher the flow rate the more gas I
>seemed to lose. After removing the bioballs, you may want to play with
>keeping everything constant and decreasing the return rate to the lowest
>flow that is still adequate for the tank. See if that lowers the pH some.
>The higher the return rate, the more surface turbulence, the more
>I can only think you probably have a fairly powerful return pump with your
>need to pump to a minimum 15' or so head height from your basement. You may
>already have the output side of the pump ball valved since you are a Reefer
>as well. Reefs like high flow rates, whereas planted tanks don't, and really
>need decent circulation with a calm surface.
>Another thing you can do that I failed to mention is to
>Aquatic-Plants mailing list
>Aquatic-Plants at actwin_com
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