pH cycle...too high?

[untamed]

Now that I've begun to monitor the pH, I can see that the tank is reaching a daily high of over 8.8. That seems unusually high to me.

I've just recalibrated the sensor, so I believe the readings are accurate.

I'm running my Ca reactor at only a pH of 6.8. I'm not dosing Kalk.

Do you think this is something that warrants some kind of correction?

I still have a lot of algae growth. Could it be that I just getting a large amount of photosynthesis taking place that is driving the pH up?

[Delphinus]

Oops, I posted my thoughts in your journal thread. Errr, sorry about that. I guess for posterity I should copy and paste them into this thread:

Originally Posted by Delphinus

Wow, that does seem high. IMO though, in and of itself, the number shouldn't cause you concern if the livestock appears otherwise healthy and happy and whatnot. Ie. I think people tend to focus too much on things like "Oh no! My tank's pH is 8.1 and everyone else is at 8.4, I should add some pH up or something" - which is folly because the pH itself is only a summation of other variables at play. And of course, if the tank is doing fine at 8.1 then one shouldn't worry about it not being 8.4.

But, I have to say I'm a bit surprised to see those numbers if you're running a calcium reactor. I thought running a reactor tended to pull the #'s downwards. For example, on any tank I run, typically I see pH swings around something like 8.1 to 8.5 without a reactor on a tank, and about 7.8 to 8.2 when there is a reactor on the tank.

Sooo anyhow I have no idea what to make of your #'s, that is interesting indeed, although like I said if your livestock is otherwise doing fine I wouldn't sweat it too much.

Maybe because your tank volume is so large it has an easier time shedding any excess CO2 from the reactor?

It could be that the photosynthesis from the algae has an effect ... but .. exactly how much are we talking here? I would not have guessed that the effect would be so profound on 400 gallons..

[untamed]

Its a two stage reactor, so it probably isn't affecting the tank as much as might be expected....and I'm only running the reactor at 6.8.

My Ca/Alk demand is such that I could turn the reactor up....based on the current pH, I think I'll drop the reactor pH a bit and see if that causes any affect upon it.

There is a good chance that the 48" x 72" surface area, as well as two sumps (18" x 36" & 24" x 48") might be contributing to better-than-usual gas exchange.

I also think that I can see the effect of glas cleaning in the daily fluctuation. When the glas is cleaned, the cycle is slightly lower. As the glas greens up, the cycle gets higher.

[michika]

Like Tony said, I wouldn't worry about it. Many reef environments reach 8.8 for pH. If things look great, and your not having any problems I wouldn't panic.

[adidas]

my ph is always between 8.3 and 8.7 - 8.8.

[untamed]

Thanks...that makes me feel a lot better.