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View Full Version : Can't keep pH Up - CO2?

captainandy
08/20/2008, 04:46 PM
Very frustrating. Have 150 gallon reef (SPS very heavy) plumbed to basement 200g fuge (has large Tunze to circulate) then 100 gal sump. For the past several months I've been having to add, almost daily,pH buffer to keep system above 8.0.
Top off with continuous Kalk, large Knop calcium reactor. Don't know what to do next.
Added a fan over the sump/fuge a month ago (possible carbon dioxide) without effect.
I will be switching to Two-Part next week but this still doesn't make any sense to me - considering the set-up is several years old and this problem is onlly past few months.

Salifert tests:

KH 10 - 12
Ca 430
Mg 1400
temp constant 78
phos, etc undetectable.
RBU1
08/20/2008, 05:16 PM
What I would do is take some of your tank water in a cup and put an air stone in it for a little while then test that water. See if your ph raises.
reefpepper
08/20/2008, 05:36 PM
i agree, but do that outdoors in fresh air. CO2 was my problem until i ran the skimmer air intake outdoors.
captainandy
08/20/2008, 05:43 PM
great suggestion. Interestingly, when I mix up fresh saltwater, the pH is around 8.2 and stays that way. I also just moved my vortechs close to the surface to cause a lot of surface agitation.
Boomer
08/20/2008, 05:46 PM
You may have excessive CO2 and it may be coming from the Ca reactor. Single phase Ca reactor are famous for this. You should not be adding buffer for pH, that just makes things worse.

Added a fan over the sump/fuge a month ago (possible carbon dioxide) without effect.

That may do nothing as you blow out the air and it just comes back in. What you need is a duck line form the outside that pulls in fresh air and another duck line that blows it out and each with their own fan. Also get a second media reactor and have the Ca reactor effluent dump into it. This will raise the pH as it will remove some of that CO2.

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm
captainandy
08/20/2008, 06:46 PM
Just realized that I had cut the photoperiod of my fuge in half to save money this summer. Running a 1000W metal halide to keep a few big mangroves looking good.