Low PH

[omoreno]

I have a 55 gal that I have been running for about almost 9 months. I have been using Aquarium Pharmecuticals tests kit. But lately, I have had drop in PH to about 8. So I decided to purchase a Salifert KH/ALK test and a handheld Hanna PH meter. After I calibrated the PH meter, I have found that the PH was actually about 7.8 and that is after an 8 hour photoperiod. Wanted to see what you guys think next course of action for a noob reefer. Dose Kalk? Here is some more info on the tank.

KH = 9.3 dKH (salifert)
ALK= 3.31 meq/l (salifert)
ph= 7.8 (meter calibrated)
sal= 1.024
temp= 81
HOB Remora skimmer
lighting= 2 x actinic, 2x10K, photoperiod 8 hours
water changes = 10% every 2 weeks
salt = oceanic
livestock= fire goby, yellow tang, 2 clownfish, royal basslet
soft corals= mushrooms, xenia, button polyps, a few zoos
Any help is appreciated....

[matt]

What are you using to replenish calcium, and what is your calcium level? That's the first place to start. Another real possibility, if you have a well sealed house with lots of humans (and/or large dogs!) is CO2 build up inside the room the awuarium's in. Usually this only happens to people with large families in the winter in a cold climate, where outside air is really kept out.

Unless your calcium is low, or you're using calcium chloride (turbo calc) a lot, I wouldn't know what's causing your ph to dip, aside from normal metabolic stuff that tends to depress ph. Have you checked it in the morning just before the lights come on? Bet it's not too much lower than 7.8, if your dkh is 9.3. Oh yeah, one other thing, you don't describe what kind of lights you have; vhos, power compacts, or normal florescents. If they're only N.O. tubes, maybe you're not getting enough photosynthesis in the tank to produce the oxygen that typically drives ph up during the day in a reef tank. I'd also increase the photoperiod; maybe 10 hrs with the 10ks, 12 hrs actinics.

[NaCl_H2O]

Another real possibility, if you have a well sealed house with lots of humans (and/or large dogs!) is CO2 build up inside the room the awuarium's in.

I have a 2200 SqFt home, 4 people, 4 small dogs, and we smoke. I ran an air line up through the attic to a vent and feed my skimmer off this air line in addition to a small rio w/venturi in my sump. The "Fresh" air supply made a HUGE difference in the Calcium level I could maintain in my tank, and thus the Alk & PH levels. My PH still remains somewhat low (7-9 - 8.1). If you have central air, and lots of people/pets (or smoke like us), I recomend tring the outside air supply. Just run some airline tubing out a window & try it for a day or so.

[cvonseggern]

I'm getting much more consistently high pH since I started aerating my RO water for 24 hours before mixing it. The theory being that the aerated water has more dissolved oxygen and doesn't eat up as much of the buffering capacity of the salt mix...might be worth a try.

[omoreno]

Thanks for the tips...definitely something going on. I took a PH reading this morning before the lights come on and the PH was 7.5, yikes. Took another reading late in the photoperiod and it was 7.7......All the animals look fine except for the 1 of the red mushrooms, it has developed a white discoloration on the edge of the shroom. Fish seem okay.

My lighting system of 4 - 65w PC( 2- actinic and 2 - 10K). I am not dosing any chemicals other than some Zooplex and Phytoplex. I have a pretty strict water change regiment( 10%/ 2 weeks).

I also took a calcium reading using a Hagen CA test kit (its the only 1 have, i might purchase a salifert here in the next few days) and resulted as 480ppm.

I also added some egg crate to 1 side of the tank to see if this helps for gas exchange and have added 1 hour to the photoperiod. I will extend this slowly out to 10 hours.

The saga continues.......thanks

[matt]

If you have a decent skimmer and you're using outside air to feed it, I think you can rule out the CO2 issue. I'd check something called ORP; oxygen redux potential. I think it's basically a measure of dissolved organic activity in the water, which produces acids and affects ph.

Initially, maybe get a hold of some washing soda or drip some KW to get the ph up a bit. Oh yeah, one other thing, you should remove a sample of water from your tank and stick the ph probe in it rather than just stick the probe in your tank. Calibrate your meter, and let it sit for a good minute or two in the calibration fluid, then rinse it, put it in the sample well away from the tank (stray voltage, interference from lights) and then let it sit for a while before reading. If you really have Ca level of 480, ( the hagen kits tend to read high IIRC) dkh of 9.3, and a skimmer running with fresh air, I can't imagine why your ph would dip that low, unless it's somehow connected with the ORP, and I'm kind of guessing because I don't know that much about it. Good luck!

[omoreno]

Thanks for the additional info. Will do a change this weekend and work on the ph. Thanks to everybody that contributed.