Low PH

[IslandCrow]

My PH seems to be chronically low for a reef aquarium, hanging at around 8.1. As I understand it, it should really be up around 8.3. I've been using reef buffer to keep it around the 8.3 range, but what I'm wondering is whether I'm just masking the symptoms of an underlying problem. Should I just be happy that I can keep it at 8.3 with the buffer, or is there something I'm doing wrong that I can fix?

I imagine you'd like some background info:

Tank: 55g reef (just a couple soft corals)
Lighting: 96W PC (it'll be upgraded eventually)
Flow: 2 x 295gph Maxijet powerheads (just recently added the second)
SG: 1.025
Ammonia: 0
Nitrite: 0
Nitrate: 3-4ppm
Phosphate: .5ppm or less

I haven't checked alkalinity in awhile since the test I have for it is kind of a pain, and I've been told it isn't very important to check religiously, but it was always towards the low end as well. I've never checked calcium, but I don't add any supplements and do 10% water changes each week.

On a side note, I know reef aquariums keep a higher PH than ocean water. Why is that?

 

[Randy Holmes-Farley]

IMO, a pH of 8.1 is fine for a reef aquarium. Also, buffers are not a good way to raise it as that only boosts alkalinity. If you want to raise it, limewater and/or aeration with fresh air are the way to go.

This article has more info:

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm

 

[Anemia]

Open the window near your tank and see what happens.

 

[IslandCrow]

Thanks for the link to the article. I think it's shedding more light on why many people with reef tanks have slightly higher PH than is normally found in seawater. One interesting thing I got out of the article is, if I'm understanding it correctly, you can determine whether or not you're getting sufficient aeration and your CO2 levels are acceptable by the relation of your alkalinity to PH.

As it is, I think I'm much less concerned about my current PH levels. Since I only have soft corals right now, I'm not as concerned about keeping my calcium levels high since they seem to be doing just fine with regular water changes.

 

[Randy Holmes-Farley]

whether or not you're getting sufficient aeration and your CO2 levels are acceptable by the relation of your alkalinity to PH.

Yes, although it will reflect CO2 in the air you are aerating with, and not just the actual amount of "aeration".

As it is, I think I'm much less concerned about my current PH levels. Since I only have soft corals right now, I'm not as concerned about keeping my calcium levels high since they seem to be doing just fine with regular water changes.

Sounds good. Just don't let them drop too much or coralline algae and even some soft corals may suffer.

 

[IslandCrow]

Well, I tested some newly mixed water that was very well aerated and compared the PH and alkalinity to the water in my tank, and it's looking like a combination of CO2 levels in my house slightly higher than I'd like them and not quite enough aeration in my tank. My PH in the tank is holding pretty steady between 8.1 and 8.2 with an alkalinity of 3.5 or possibly slightly higher (my current test kit is only good +/- .5). Not perfect, but it doesn't look too horribly bad when I reference the chart relating PH & Alk to CO2 levels. The tank's near a window, so I can open that on warmer (or cooler in the summer) days, and it sounds like if I start to dose with kalk, that could force the CO2 level down as well.

 

[Randy Holmes-Farley]

My PH in the tank is holding pretty steady between 8.1 and 8.2 with an alkalinity of 3.5 or possibly slightly higher

That looks good to me. Limewater (kalkwasser) would raise the pH more, but that isn't necessary.