empty tank, low pH?

R

ReefTourist

New member
I have a brand new 90g tank w/30g sump, and just added a 2" layer of southdown sand.
I just finished letting the sandstorm settle in my tank, and was able to turn the return pump on last night. The pH and salinity were low since I had drained the sump to clean it and refilled w/ RO/DI water, and the display water had been sitting still for several days.
Now I've raised the SG back up to 1.022 (headed for 1.024), but the pH is staying at 8.00 12 hours later as tested by my pH meter and test kit. I also ran the calcium test for the first time last night and had a result of 250 ppm.
I'm using InstantOcean salt. I would think that as I add salt the other trace elements in the salt would buffer and raise calcium levels. However, even as I'm reaching my target SG the pH is failing to rise. Am I missing something?
I'm hoping to add LS today and LR very soon, but want all the parameters correct before. Any ideas?
 
BTW, alkalinity is measuring about 3.5 meq/L.

In reading the article here it looks like the best explanation for why the pH is failing to rise is CO2 levels since the tank was sitting still forever. I guess I need to be more patient and wait for awhile for the pH to rise as the water is aerated.
Anyone agree/disagree?
 
Yes, I'm talking to myself... a quote from the above article:
"For example, if the aquarium has an alkalinity of 3 meq/L (8.4 dKH) and has a pH of 7.93, then the aquarium must have excess CO2 in it (or else the pH would be just over 8.3)."
That's pretty close to my parameters (3.5 alk, 8.0 pH), the graph definitely looks like my params = excess CO2, and I have a reason why CO2 would be elevated - stagnant water.
Now to ask myself how long it would take just a skimmer/return pump to raise the pH... it took 3-4 days of sitting still for it to fall that low... perhaps buying an airstone for situations like this would be helpful.
 
I wouldn't worry about it if I were you. 8.0 is fine for cycling. Lower PH is actually desirable in that ammonia is not as toxic at lower ph.

Once you near the end of the cycle, and need to try to raise it (not that you do, 8.0 is fine), if airation doesn't work (which would indicate high atmospheric CO2 in the home) kalkwasser works nicely, or randy's formula 1.
 
Yes, you will want an airstone to speed things up. There are other factors as well.

Is your tank covered, or an open top?

How old the house yuou live in? If it is newer, and/or has a high energy rating, that means that there isn't as much oxygen exchange going on in your house. You may need to run an airline outside and continuously bubble an airstone in your sump.

Get your S/G to 1.025 and give it a few days. If it is still all out of wack you may want to look into pickeling lime (kalkwasser).

How are you mesuring everything? (digital meter, test kit (what brand, etc.) If it was a digital meter did you calibrate it?

As for the calcium, Personallly I have always had a problem with low calcium coming from Instant Ocean. Hence, why I now use something else. But, don't add liquid calcium yet!!! As your PH rises, your Alk will fall forcing your Ca up.

Hope this helps some..
 
Thanks for the responses. Talking to yourself is not as productive. ;)

- Tank is uncovered

- house was built in '88, and the windows are drafty so I doubt low CO2 in the house is a problem

- used a brand new digital meter that I calibrated yesterday (although that was a finiky process). Also used a Salifert pH test as well that pretty much mirrored the digital readout.

- Since I don't have any coral yet I expect the calcium demands to stay pretty low for awhile. Thanks for the tip that as pH rises alk will drop and calc increase. I'll do some more reading, keep an eye on it, and supplement or switch when the time comes.

I understand 8.0 is on the lower end of being ok, but with nothing in the tank I would expect it to be higher. (Before I added sand and stopped the pumps my test kit measured ~8.25.) After reading, and your helpful thoughts I feel better about starting the cycling process. I'll get an airstone to help now and in the future, and keep an eye on it.
 
Hmm, I wouldn't use an airstone because they make a mess. Does the tank have a skimmer? That can help with aeration. Other than that, if there is live rock curing, the metabolites of that process often drive pH lower.
 
There is a skimmer running, there is no live rock, it's an empty tank...
Just recalibrated the pH meter at the LFS - 7.8 in the tank.
I think it's water change time.
 
The problem with using buffers to control pH is that alkalinity tends to shoot through the roof. A lime drip can help with pH, but it needs to be added into the supplementation scheme for alkalinity and pH. Since this tank is empty, I don't think that's going to work all that well.
 
Plus, I shouldn't have to buffer an empty tank. It should be at a perfect level w/ no demands affecting pH at all. Only thing different was the addition of non-live sand, and a 4-5 day standstill.
 
Apparantly I can't calibrate the pinpoint correctly, and neither can the LFS. Right now I trust the Seachem test kit over the meter, and the kit's reporting a nice 8.0 which is still low, but at least not dropping like the meter is reporting (last was 7.72 until I messed w/ it some more)
Seeing such a low level, but not trusting the "more accurate" meter is so frustrating.
I've been messing with this measurement all day, and now I just give up. I'll call it 8.0, bring up the SG to 1.025, and get ready to start the cycle since that will throw off all the values anyway.
 
So there's nothing in there yet? I wouldnt worry about parameters other than SG until after your rock and sand is in and the tank is cycled. You'll be doing a big water after the cycle anyways.
 
Thanks graveyard. I've been wanting everything to be perfect pre-cycle, and it was.. until I added sand and let it settle. Now they're a bit off, but liveable. And after today I'm at that point of not worrying about it, fixing SG, and ordering LR tomorrow.
 
Once you put in the sand and LR and the cycle starts things are gonna get pretty messed up anyway. It wouldnt hurt while the tank is cycling to monitor ammoniaand change some water if it gets over .5 ppm. Other than that I wouldnt about the other parameters aside from SG.
 
Update: I found that the pinpoint calibration fluids I was using were way off. When I went to recalibrate again at the LFS we found my water at ~8.12 after recalibration which matched their meter. Before this it was reading a crazy 7.39 :eek2:

So needless to say I was right in trusting the drop color test in the meantime, and now I feel much more confident in adding LR in a couple of days. :cool:
 
When I first ordered the calibration fluids, they sent me rinsing fluid instead of the PH7. The package looks very much like the PH 7 calibration fluid. Make sure yours is not rinsing fluid.
 
I checked, but it says calibration fluid (both 7 and 10). I'm sure it's reading correctly now that we used other fluids.

Let me also give a big thank you to all those LFS folks that take the time to help people with equipment problems even if they didn't buy the equipment there. It makes your shop feel... like home... an intangible quality that definitely will make up for it in future sales.
 
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