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gndn
12/03/2012, 04:36 PM
Please help, I need some advise on my new tank and what to do about a low PH.

I know this question has been asked over 1000 times, and trust me I've done TONS of research, but still just don't seem to be getting why my PH is SOO low.

I've recently setup my first saltwater 90 gallon tank and I've built a 30 gallon sump. I've taken my time to research just about every aspect of the hobby taking months before I even put the tank together but I am not sure what to do about my PH being soo low.

My build:
90 gallon display
30 gallon sump
100 lbs dry rock
60 lbs dry sand
3 lbs of live rock
90 GPD MaxCap RO/DI

Testers:
Neptune Apex with a probe that I calibrated, and two separate API High Range PH Test Kits.

I've had my tank running for about a week and a half with the saltwater and sand in it. The first go around I made the mistake of using reef salt to start off with, and everything was testing fine except my calcium was over 700. I got rid of all the reef salt and switched to IO salt and got normal readings of everything and 500 calcium so I knew I was good. I let all the dry rock and sand and everything run for about a week, then added 3lbs of live rock with coraline algae on it from the best saltwater store in town (rep wise).

The problem is my PH seems to be anywhere from 7.9 to 7.5, but on average hovers around 7.7. I've confirmed these PH reedings using a Neptune Apex PH probe that I calibrated using the SetPoint 10.0 and SetPoint 7.0 packets, and I've also tested this with 2 different API test kits that expire in 3 years from now. Below is a graph of the last 4 days for my PH from my Apex.

http://img838.imageshack.us/img838/1199/42223819.jpg

Possible thoughts...
I built everything myself including the stand, the hood, the plumbing, and the sump, and since it sits in my living room I specifically designed it to be a quiet as possible. I've successfully done this by ensuring there's no air or gargle in my drain pipes, and the overflow in the Reef Ready tank is up near the top so there's nearly no waterfall. However I know that PH is a direct result of air exchange at the surface of the water, but since there are basically NO bubbles in my system, the only gas exchange is in my protein skimmer in the base of my stand, and the surface agitation of the display tank which is covered by my hood. The hood isn't sealed but it's pretty closed up.

Please help point me in the right direction as I've tried several things I've seen from trying to research but I must just be missing something for it to be this low.
disc1
12/03/2012, 05:20 PM
That's not very low to begin with. Just on the low side of normal. Low pH is common during the cycle in process because of all the bacterial action. Hold on until you've got your cycle finished before you start fretting over pH.

Do you know your alkalinity numbers? That's far more important than pH. If it is running really low then pH will tend to run low.
disc1
12/03/2012, 05:29 PM
The last twelve hours of that graph look a lot like a probe drifting. I'm not sure the pH has really gone that low. Those color changing kits aren't very accurate, especially on the ends of the range.

If you recalibrate the probe does it read any different?
gndn
12/03/2012, 05:33 PM
my Alk is 10dKH
gndn
12/03/2012, 05:37 PM
The last twelve hours of that graph look a lot like a probe drifting. I'm not sure the pH has really gone that low. Those color changing kits aren't very accurate, especially on the ends of the range.

If you recalibrate the probe does it read any different?

I don't have any calibration solution on me but it's possible it could be drifting, is that normal for most ph probes? Or do you think I should invest in a different probe?

As far as the other comment about the color ph test not being accurate, I was simply including this in the comment because all three tests were indicating the PH was somewhere between 7.6 and 7.8.
aNDoN
12/03/2012, 06:22 PM
if your tank is dark at night (no refugium running a light cycle opposite your tanks) the pH will drop. IME, IO tends to run a little low on pH. Normally around 8, and 7.8 with reef crystals (obviously not always but this has happened to me many times). It may be a PITA but with a controller that actively displays pH, dosing pH+ shouldn't be all too bad...
gndn
12/03/2012, 06:30 PM
if your tank is dark at night (no refugium running a light cycle opposite your tanks) the pH will drop. IME, IO tends to run a little low on pH. Normally around 8, and 7.8 with reef crystals (obviously not always but this has happened to me many times). It may be a PITA but with a controller that actively displays pH, dosing pH+ shouldn't be all too bad...

Thanks for the advise. I do have a light running on an opposite schedule in my refugium as I read about the PH swing between day/night, but looking at the graph the up and downs don't really coincide with anything, it just appears to be completely random to me.

As far as dosing, I'll probably wait for a full cycle before trying to add any chemicals because I do understand things could change a lot between now and then, I'm more just looking for if this is normal at this early in the game or if there's anything I might have wrong in my setup.
aNDoN
12/03/2012, 07:12 PM
nah man. your setup is fine, don't fret. you will work it out just keep an eye on it and make it right if need be when the time comes. leaving it the way it is has absolutely no adverse effects on nitrifying bacteria.
disc1
12/04/2012, 12:21 PM
dosing pH+ shouldn't be all too bad...

Except that it will drive up alkalinity and make the low pH problem even harder to fight once it comes back to equilibrium.
Driver13
12/04/2012, 12:52 PM
Let that bio load even out, and keep 8 hours of light on the tank every day. It will balance out in time.