pH, alkalinity, and calcium question

[arking_mark]

Not quite sure what equations that is using, but I just recalibrated everything and used a different Hanna checker and got the same results. pH is averaging 7.76 +- 0.02. As someone else suggested, I took an air pump and some tank water outside and let it aerate for about 20 minutes then did a pH test and came out with 8.0, which while better is still not in the 8.3 - 8.6 range I keep seeing recommended.

At this point I'm looking into ways to inject pure oxygen into the tank, rather than room air.

There is a mathematical model for the ocean CO2 system. Basically, given any two measurements from Alk, pH, or CO2 you can calculate the 3rd.

Outdoor air is around 400ppm CO2. Unfortunately our hobby grade pH and Alk measurements aren't great. If you trust one of them you can calculate the other after aerating the water for about an hour with outdoor air.

O2 has no impact on the model.

 

[Privateye]

Randy's totally right that you probably shouldn't shoot for 8.3-8.6. It's not realistic for most aquariums and I'm concerned you could harm the coral and/or fish by trying. It's a pretty artificial environment.

I know it's confusing seeing so many conflicting things online, and especially in forums, but there are reef chemists and biologists weighing in on your post here. 8.0 is totally fine IME for SPS, LPS, and soft coral. I haven't seen one coral give me any indication that died from 8.0. Keeping it stable around there could be far more beneficial than trying to keep boosting it to an artificial level.

The good news is you found a way to increase your pH that doesn't risk any harm to the inhabitants. A little aeration should make things better, and the nice thing about aeration is that by continuously adding air you're stabilizing O2, CO2, and indirectly your pH as well. As any old fish guy will tell you, a big change in pH can be more lethal than an extreme pH.

 

[Mo.]

So I just bought a Hanna checker for both calcium and alkalinity. Right now my tank is sitting at 7.82 ph, 13.7 dkh, and 443 ppm calcium. I am thinking my pH is too low. I have two sps and have read that ph should be in the 8.3 to 8.5 range. I've been reading the article below. It's a DIY mix. Is this still valid and workable or should I do something else?

http://reefkeeping.com/issues/2006-02/rhf/index.php#3

On another note, how do I adjust the ph without mucking up the other readings? I've tried baking soda, but it tops out at 7.89.

Thanks!

Assuming your alk didn’t just spike- If you have only 2 sps. Don’t mess with your system. Leave it to slowly drift your alk down. Your corals will be fine with the current parameters and slowly drift to say 8.5 or 9 alk. They will NOT be fine if you keep tampering with parameters and chase the numbers. Your pH is also fine forever at this level, although it would be nice to have it in the 8 or 8.3 range it is not essential.

I would let my alk drift downwards by reducing the alk dosing if it were me.

 

[Mo.]

At this point I'm looking into ways to inject pure oxygen into the tank, rather than room air.

Huh? What?

you’re certainly looking at ways of crashing your tank.
Your current ph is fine it won’t harm your tank!
The alk is a little high.
What is your salinity and calcium doing?

Leave your tank alone!