Question about PH

[Bernardhny]

Hello all,

Please let me thank everyone who reads this and posts a reply in advance. I think for any diagnoses you will probably need to know about my tank:

55G Square tank.
3" of Live Sand
75 pounds of live rock (all of the rock has been in the tank since Feb 2012)
Remora S Pro Protein Skimmer running 24/7
3 Hydor Koralia Power Heads hooked up to a wave maker
T5 Lighting (4 bulb)
EShopps 75 Sump setup as Refugium (15 pounds of live rock), Miracle Mud, Chaeto and a few other beneficial algaes growing nicely)
BRS GFO/Carbon reactor
UV Filter
RO/DI filter putting out 0 TDS water. I keep two 35 gallon tanks (one fresh RO/DI and the other Salt Mix)

Water Chemistry: Nitrates 0, Phosphate .5, Cal 460, Alk 8.9, PH 7.8, Salinity 1.025

I do 10 gallon water changes every Saturday morning. Clean the skimmer every saturday, blow off the corals every saturday, feed the fish twice a day (flake in the morning, frozen at night). Tank looks great.

BUT
No matter what I do, or what I try, I can't get my PH to stay around 8.4. I can't keep my ALK around 10 (when I do get the alk to go up, the PH goes up to my desired range, but within 24 hours, drops back down. I can literally go through a bottle of part B per week and have no steady results. I can't figure out what is leeching the alk so fast and why I can't get my PH to stay up. The first question I expect to read is why I want the PH at 8.2 or 8.4 and the answer is my corals seem to thrive at that level, better color, more extension etc. The crazy part of this is what happens when I make the RO/DI water. I know this is going to sound crazy but when I test my water in the 35 G fresh water tank (both tanks are the same btw) the PH out of the RO/DI is around 8.8 (a bit high for RO/DI but I have verified this number to be accurate and my ph meter is calibrated against 7.0 and 10.0). When I make a 35G batch of Salt from this RO/DI water I expect the PH to stay at the same level or at least drop to the guaranteed analysis for the salt at the temp to 8.2. It drops from 9.0 to 7.6 - 7.8. To combat this I was told to treat the RO/DI water with RO/DI right or another chemical to replenish the good stuff the RO/DI process removes. This does not help the PH.
Does someone see the error in my ways? I am not sure what I am doing wrong. I thought about getting a 2 part doser and trying to combat the alk and ph problem that way, or getting a calcium reactor. But I have read that a calcium reactor can just cause greater PH problems. I am at a loss.
Thanks

Bernard

 

[Mike J.]

A couple things not mentioned are magnesium and how much calcium and alkalinity is being used by your critters.

Magnesium is the first step in dosing. Without a proper mag level nothing else will work right. And why are you chasing numbers?

Just sounds to me like you're dosing without a reason, and that's what the problem is.

 

[Bernardhny]

Magnesium?

I knew that Magnesium played a part but I didn't realize that it had so much to do with PH and Alk. I will have to get a test kit and check the levels.

Thanks!

 

[Mike J.]

First, I'd have to know how much your critters are using. I'm assuming that you're chasing your tail and what you really need to do is regular water changes without any additives to find out what your true levels are and then work from there. First you need to know a depletion rate before you start dosing anything.

 

[Planedoc]

Co2 in the air drastically effects ph. My ph is 8.3 on a nice day with the doors open and 7.8 with doors closed. Fighting to keep a high ph is almost a waste of time. Keeping your alk, cal, and mag levels correct is best. You can run a line from your skimmer to outside your house to help with co2 if you think that might be a problem.
Test your ph and then open doors / Windows for 4 or more hours and test again. You will be surprised.