pH is running at 7.8

[matty-dog]

Hi all. I think I may be in trouble and could sure use some help and or explanation regarding how pH and Alkilinity work together in a reef system. My reef tank is a 120 gallon reef with approximately 400 pounds of well cured rock. All my water is made up from a Spectrapure RO/DI unit with a automatic replentishment system. I also add calcium via a Calcium reactor. I also suppliment with Bionic, Strontium and Iodine. I was shocked the other day when I took my pH probe out of the small cup I use to monitor the output of the Calcium reactor and put the probe directly into the sump. My pH reading was 7.6 in the main system... no wonder my corals look tired and lacking... Just short of a panic I started adding Seachem's Marine Buffer but the pH is coming up so slow that I'm wondering if I'm in more trouble than I realize. I'm going to test my alkilinity later this afternoon but in the mean time I could really use some help understanding which way to go to recover my pH and not have this problem happen again. Any help would be greatly appreciated. Believe it or not I've been in the reef hobby for over 10 years and havn't ever had this happen before... Thanks in advance, Matt

[zhenya]

Hi Matt, Welcome to Reefland

Give this article a read through. In short, there could be a few possibilities, from high CO2 in the air to low alkalinity. If you use Calcium reactor, I would recommend using kalkwasser dripping at night instead of using any buffers or the B-Ionic. When I just started using my reactor I had similar problem as well. Slowly it went away.
I also think that if you have your pH probe close to the reactors effluent discharge you might be picking up wrong reading.Try placing that probe in the tank somewhere for 10-15 min. and see if you get different reading.

here's couple more articles related to this:
http://www.advancedaquarist.com/issues/may2002/chem.htm
http://reefkeeping.com/issues/2002-0...ture/index.htm

[acropora]

That was some excellent advice above by zhenya. I also agree that Kalk additions will help. I use a Nilsen reactor in addition to my calcium reactor.Another factor is the availability of fresh outside air. I constantly struggled with a lower Ph with a set up that was in my basement. however it remained constant and overall was not an issue.