ph in reef

[jas217]

Hello Randy,
I have a 90 gallon reef with mostly spsc all are growing good, my sump is 29 gal and 20 gal refugium. I use red sea salt at a sg of 1.023. the alkalinity is 2.5 meq/l, the calcium is 425. I drip kalkwasser at 2 tsp gal and add 30 ml of b-ionic 1 and 2 daily. My ph never gets above 8.1 and was wondering although all my stoneys are growing well should the ph and alkalinity be higher. It seems that most tanks are running much higher in both departments. Thanks for your time your doing a great job.
Joe

[Randy Holmes-Farley]

Thanks, Joe. I'm glad people are finding it useful:)

While I too would have expected a pH higher than 8.1 for a tank with additions like yours, 8.1 is perfectly OK, and I'd be hard pressed to say that any other pH is actually better.

One question, when you say it never gets above 8.1, does it ever get much lower, or is it pretty steady at 8.1 in both the morning and at night? Also, how are you measuring the pH?

[jas217]

Thanks Randy, The ph always stays between 8.0- 8.1 measure ph using seachem ph kit. Perhaps kit is not very reliable? thanks again Joe

[reefer2078]

try saltfert test kits!!!!:D

[Randy Holmes-Farley]

pH test kits often aren't esapecially accurate, so I wouldn't worry about it. If it read 7.8, I'd try to determine what was going on, but at 8.1 there's no problem, and if it really is 8.3 or 8.4, that would be more normal for a tank like yours, but not necessarily any better.

[Playfair]

Since running a Ca Reactor on my 120 I bearly reach 8.0 H, and normally the tank runs at 7.8-7.9 night and day. This is measured with a freshly calibrated Hanna pH meter.

I'd really like to avoid dosing kalc to up this level, simplicity is why I added the reactor. None of the tank inhabitants seem worse for the wear...

The reactor is outputting 200ml/min at a pH of 6.7/6.8

Guess I am wondering what long term effects this might have?

ps- If you happen to be in the Roch area on the 26th of this month, I am hosting our reef club meeting :)

[Randy Holmes-Farley]

Lot's of people with calcium carbonate reactors run a low pH without apparent problems. Unfortunately, limewater is probably the best way to raise the pH. Increased aeration of the tank can also do the trick, by blowing off some of the excess CO2. Engineering the reactor to blow off some of the excess can also help, but it can not completely solve the problem.

What's wrong with low pH in conjunction with high alkalinity that often occurs in a reactor tank? Not nearly as much as in a limewater tank where the low pH would also mean low alkalinity.

Two possible issues concern me:

1. Phosphate may be less inclined to be scavenged by CaCO3 in a low pH tank. Sand, rock, and growing CaCO3 skeletons and abiotic precipitation of CaCO3 (like on a heater) are all places that can suck up phosphate, but it is more effective at higher pH.

2. At low enough pH, aragonite becomes soluble, and coral skeletons may begin to dissolve (which I presume is very bad). In seawater, this begins in the mid 7's, but in a tank with higher alkalinity than seawater (2.5 meq/L) the pH will have to be lower (mid to low 7's).

Unfortunately, I have to get back to work on Monday and will be leaving Webster this weekend. Please keep me informed about future meetings!

[Playfair]

Thanks Randy, great reply. I do have a couple of ideas I think it's time to put to work to get rid of access CO2 in the effluent...

One involves making a coiled effluent line which will promote this bright green stuff that grows in my current line. Of course, I am assuming this is some form of algae that gets indirect light from the refuge/sump. IF it is a plant and not bacteria (how can one tell?) then it consumes C02. Thus I would have a sort of "coiled de-C02er".

The other idea is to allow all the effluent to out gas openly in front of my exhaust fan, thus C02 should never get near the waters surface. This involves putting a Tee in effluent line, which is metered right out of the reactor, and hope that the gas takes the additional path (needs more consideration).

I'll post results, especially if they are promising, since so many seem to suffer this pH depression problem.

I currently have a 2nd stage on my reactor, though it doesn't seem to have much effect. I don't understand how CaC03 saturated effluent from the first stage, can dissolve more when the pH is the same, or higher in the 2nd stage...

ps That's too bad about the meeting... If you ever do want to "hang" and check out any reefs or go to CF, just drop a line!

[Randy Holmes-Farley]

<< I don't understand how CaC03 saturated effluent from the first stage, can dissolve more when the pH is the same, or higher in the 2nd stage...>>

Your right. If that were true it should have no effect. The idea presumably is that the water is not saturated with CaCO3 at the pH that it enters the second chamber, and that dissolving a bit more CaCO3 drives up the pH.

<< The other idea is to allow all the effluent to out gas openly in front of my exhaust fan, thus C02 should never get near the waters surface. This involves putting a Tee in effluent line, which is metered right out of the reactor, and hope that the gas takes the additional path (needs more consideration). >>

I don't know the details of this setup, but I'd put more money on this than the algae. The algae will suck up some CO2, but maybe not enough to notice.

<< If you ever do want to "hang" and check out any reefs or go to CF, just drop a line!>>

Thanks:)

[acrophoria]

i have had a prec. marine ca. reactor for about a year now and my ph was always 7.8 7.9 during daytime with mostly sps.had a few losses.started kalk. drip bucket and ph at night is now at a steady 8.0 and day time 8.24 pinpoint monitor.
my bucket was easy,5 gal.hole drilled 2 inches from bottom,air line tubing siliconed on place,and those little blue plastic valves total cost $5. reason for hole 2 inches up so you dont get powder in your tank you just get limewater.also i drip 1 drip every 6 sec.
72 bow 75 fuge.175 ushio, bullet skimmer,pm reactor