Raising pH without raising alk/calc

[Kairus]

I just set up a 20g high with rock, sand, and water from my main tank, and my pH is really low, like under 7.8. My lights aren't here yet, and I don't have a skimmer for this tank, I have an algae scrubber, but it's brand new so no growth on it. On my main tank I drip kalkwasser which keeps my pH above 8 at all times. I don't think I can drip kalk on this tank though, my calcium demands are going to be almost zero, so eventually my calcium is going to go through the roof. I also think alkalinity will go up too much as well.

What options do I have? Just aerating the water more?

 

[spicytuna]

Is there any life in the tank? Photosynthesis from corals and algae is what's going raise your ph during the day. Obviously if you have no light, you won't really be able to accomplish that. Also how are you monitoring the ph? I also live in Florida, and this time of year when it gets hot, the doors stay closed all summer. So c02 levels rise in the house and depress the ph of the tank. When I lived in an apartment, I always had a ph between 7.8-8.0.

If I were you, I would determine how accurate the ph test is, and how will you benefit from trying to adjust it. Ph is one of those parameters that we can only indirectly control. As long as your alk/cal/mag are in check and you provide adequate aeration to the tank and the room it's in, there's not much more you can do.

 

[polleke]

I think the answer is in too little gas exchange. You don't have a skimmer, probably a small surface to volume ratio (20g high tank) and nothing yet to compensate, corals or algae.

So yes, aeration with fresh air should help imo.

 

[d2mini]

Co2 Scrubber?

http://www.reefcentral.com/forums/showthread.php?t=2309638

 

[Randy Holmes-Farley]

What do you intend to keep in this tank?

 

[Kairus]

What do you intend to keep in this tank?

This tank will have two perculas and a bubble tip anemone that split recently. I need to make room in my main tank and if I can stabilize this tank I would like to keep the bubble tip for a while and when he eventually get too large trade him into my LFS.

I'm sure the CO2 levels are high, without kalk my main tank has a low pH.

Randy, if I dosed a very diluted mixture of kalk 24/7 would that raise the pH? I thinkiI read a post where you said that even a dilute mixture of kalk has a pH of 12. Would that have much of an effect?

 

[Randy Holmes-Farley]

The limewater is the best additive that you can use to raise pH without as much alk boost. I'd suggest trying it at a low dose and see where you get in terms of pH. Presumably there may be coralline in the tank? You can probably keep the alk fairly high, which will help.

 

[Kairus]

The limewater is the best additive that you can use to raise pH without as much alk boost. I'd suggest trying it at a low dose and see where you get in terms of pH. Presumably there may be coralline in the tank? You can probably keep the alk fairly high, which will help.

Yes, a lot of coralline on the rocks. What makes limewater raise pH so much? Is it just the amount of alkalinity or is it because of its very high pH?

 

[Randy Holmes-Farley]

Not really either, although the latter is closer. It is because it provides alkalinity in the form of hydroxide ion, OH-. A few other unusual products do as well.

It boosts pH about twice as much per unit of alkalinity as does a supplement based on carbonate, which is the next best choice.

I discuss it here:

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

from it:

Figure 5. The same curves as in Figure 1 showing the effect of limewater (kalkwasser) on pH by both reducing the excess carbon dioxide (the hydroxide combines with it to form bicarbonate and carbonate) and increasing the alkalinity.

 

[dkeller_nc]

I just set up a 20g high with rock, sand, and water from my main tank, and my pH is really low, like under 7.8. My lights aren't here yet, and I don't have a skimmer for this tank, I have an algae scrubber, but it's brand new so no growth on it.

The "no skimmer" part of your post is probably key; skimmers, so long as they're supplied with air that isn't elevated in CO2, are extremely effective at ensuring that the aquarium water's dissolved gasses are in equilibrium with the atmosphere.

Moreover, the skimmer also removes organic acids that are produced by animals/decaying organic matter. These acids can have a slight depressive affect on the pH of the tank as well - this would be particularly true if sand/rock from a long-established tank that is "dirty" (i.e., full of detritus) is added to the new tank.

Having said all of that, most reef creatures are pretty insensitive to pH as long as it's somewhere between 7.4 - 8.6. However, if you're going to be permanently running this small of a tank with no skimmer and an algal turf scrubber, I'd consider using an inverse photoperiod between the algal scrubber and the main tank to minimize pH swings from photosynthesis/respiration.