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Cultivated Reef

Low pH conundrum


lonemountain

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Here is my setup: BioCube 29 (about 2 years old); upgraded Cobalt pump with SpinStream on output; Hydor Nano circulation pump; InTank media tower with Pura filtration pad (changed weekly), Purigen pillow (changed every 2 months) and bag of PhosLock, all with a pink/white filter pad on top of the tower (cleaned every other day and replaced weekly); Hydor Nano skimmer; two Ecoxotic LED light bars. Whew!

 

Here is my problem: my pH wants to lock in in the range 7.8 (morning) to 7.9 (evening). I have used at different times Kent dKH buffer and Seachem Reef Buffer, which raises the pH but only temporarily. With either I have to stop buffering as the KH gets too high. I have also tried Brightwell pH+, but that, too, is only a temporary solution. Typical water parameters measure: Ca=420/430; KH=10/11; Mag=1500 (a little high, I suspect from the buffering). All measurements are with the Red Sea kits. My pH measurements are with two digital probes, calibrated weekly at 7.0.

 

I had come to the conclusion, after some research, that my problem is CO2 related, as the tank has a pretty tight lid. My research unearthed a table relating pH and KH to CO2, and based on that table and my measurements my water has about 3.6 to 4.7 times the CO2 of natural seawater. The Spinstream has always done a pretty good job of keeping the surface agitated, and I recently redirected the Hydor circulation pump toward the surface for even more agitation, hoping for better gas exchange. To be honest, I can't say I've seen any change in the pH, even with the front hatch of the lid propped up for additional venting. Throughout all this the fish and corals (about 20 zoas, polyps, ricordia, mushrooms, leather, montipora and even a couple of SPS) have been doing fine. I use Red Sea Coral Pro salt and RODI water, mixed by weight, with weekly water changes of 20-25%.

 

I would appreciate any suggestions. My bag of tricks is about empty.

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The corals are doing fine, so don't worry about it too much. And if opening up the lid doesn't help with CO2 levels, it's likely a room-wide thing. My pH was stuck at 7.8 during the winter and summer (air conditioner means closed windows) and now that the windows are open it went back up to the 8.1-8.2 range. So long as your corals aren't complaining, I don't think a CO2 scrubber would be worth it.

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You are fine, DO NOT TOUCH A THING. I only reacted when my PH fell below 7.8, all the way down to 7.69 one night and the damage was noticeable the next day. Any reading between 7.8 and 8.3 is safe, and as Randy Holmes Farley has stated, a steady 7.8 may actually be better than 8.0 to 8.3 daily swings.

 

http://www.reefkeeping.com/issues/2004-09/rhf/

 

 

Now, second thing, are you using a calibrated PH meter to test PH. If not, ignore it, move on to more important things like KH and Calcium.

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Thanks Mariaface and markalot for the input. Yes, my pH meter is calibrated weekly at 7.0 with a stock calibration solution. Being in Arizona, our house has been closed up for months, although we have ceiling fans in every room in addition to the AC. I read of a test where you take a container of tank water outside with an airstone for an hour. If the pH goes up the problem is room environment. I may give that a try tomorrow.

 

I forgot to include, my media tower also has a bag of Azoo BioGlass and some coral rubble.

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Throughout all this the fish and corals (about 20 zoas, polyps, ricordia, mushrooms, leather, montipora and even a couple of SPS) have been doing fine. I use Red Sea Coral Pro salt and RODI water, mixed by weight, with weekly water changes of 20-25%.

 

They are fine because 7.8 pH is acceptable. Don't chase it. Don't fix what isn't broken ;)

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Try this old method.

 

Grab a cheap air pump. ($10)

An air valve. (~$3)

Some air tubing ($5)

 

Run tubing to the outside of your house or apartment. (You can usually drill a small hole on the wall to get the tubing outside).

 

Make sure the line is nowhere near bushes or grass, because apartments tend to spray bug killer spray that can damage your tank.

 

Now add the other side of the tubing inside your hood. (Not in the water, just to blow air around the water surface. If you want it to be bubbling inside your water, you will need an adjustable air valve to control the amoubt of bubbles it will produce. Like a bubble every few seconds or so)

 

That will get your CO2 levels up and maintain your ph on the 8.0-8.3 range.

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Like it's been said before don't chase the PH numbers....if it ain't broke don't fix it.

 

You could probably run a skimmer which would add O2 to your water, but if you have high Co2 in the room it won't help out all that much. You could add a co2 scrubber to the akimmer intake which would help.

 

All in all I would probably leave good enough alone. If everyone is happy, leave it that way.

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Thanks all for the advice and comments. I did run an (easy) experiment several days ago. I dropped an airstone in the first chamber of the tank and aerated it for 24 hours. I noticed no difference in the high/low pH, nor the range. I suspect CO2 is the culprit as the house has been closed up for months (summer in Arizona, you know). In a few more weeks I should be able to open up at night and I'll be interested to see if that makes any difference.

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