calcium reactor

[Markster]

I just installed a calcium reactor and want to make sure I have the logic down. First, I should add supplements to obtain the desired levels of pH, Alk, and calcium, and then use the reactor to maintain those levels. I have the water dripping into the sump from the reactor at a pH of 6.5.

[wkopplin]

I think you are one the right track. Matt can probably answer this better. He knows all about that stuff.

[matt]

6.5 is a pretty low effluent ph. Depending on your tank size and effluent flow rate, you could knock your tank ph down pretty quick. My reactor works best at about 6.7-6.8 for my size tank and calcium demand. Here's what I would do:

Get your Ca and dkh levels pretty much where you want them. Use Turbo calcium and buffer (baking soda works fine)

Test your effluent dkh; you can use a salifert alk test on the low resolution mode (2ml sample, 1 drop reagent) Ideally, you want an effluent dkh of at least 20; 25 or higher is great. Measure effluent ph as well. Since you have a really low effluent ph now, I'd start raising it by turning down the CO2 flow a bit, until you get an effleunt ph of 6.8. Then test effluent dkh again, make sure it doesn't drop too much, and you have found the right ph for your reactor. What will happen is you will find the highest ph that you can get a high alk effluent at the same flow rate. (speed of drip into your sump)

Once you've got that, you can tune the flow rate to your calcium demand; just run it as is, and if your levels go down, increase BOTH the flow rate and the CO2, keeping a steady effluent ph. If they go up, slow th the effluent and CO2 a bit. Remember, though, that depending on your media, the balance of Ca and Alk may shift. I use ARM, which results in really high dkh (10 or so) with Ca level of 400. (Not real high, but plenty IMO) The point is, your Ca level may drop a bit, but that doesn't necessarily mean you're not replenishing.

This whole process should take a week or two at least to get it stable and really tuned. Once it's there, it's amazing how stable it is. During this time, watch your tank ph, too. I'd check it first thing in the morning occasionally to make sure it's not dropping too low. I've dropped mine to 7.8 a few times as I was dialing I my reactor with no problems, so don't go running for the kalk immediately.

Good luck!

[wkopplin]

See, what did I tell ya? He has only explained that to me about five times. I never wrote any of it down and kept forgetting parts of it. Now I have it in writing and can remember what I am supposed to do. Thanks Matt. The reactor you built for me is working like a charm. It is the best piece of equipment on my tank. At least until that monster skimmer gets built.

[Markster]

Matt, my tank is a 75 gal RR. The pH controller shows 8.2, effluent pH is 6.6, effluent dkh is above 20 using Salifert low res (full 1 ml syringe with an additional .2 on a new syringe) or 21 drops using a Red Sea test kit, which equates to 11 if I remember right. Do you still think I should reduce the CO2 entering the reactor?

I have had this setup for four days now and I can see a difference in raising dkh and pH. I check the pH controller a couple of times a day and the range is reducing.

Thanks for your help.

[matt]

Just check your tank ph, Ca and dkh for a week or so, to see if you're matching your calcium load. Unless your tank ph drops, there's no reason to raise the effluent ph. If tank ph stays okay, but Ca and Alk are dropping, increase both the CO2 and the effluent drip rate. If your Ca and Alk levels start rising, you can slow down both the effluent drip and CO2 a bit.

But, if your Ca and Alk levels stay more or less okay but your tank ph drops, you'll want to raise the effluent ph a little, but not so much that you see a big drop in effluent dkh. Some reactors, particularly small ones, seem to need to run at a low ph. Also, what are you using for media? ARM supposedly works well at a higher ph than crushed coral, but that's only hear-say, mostly by the manufacturers of ARM. so, if you have a small reactor (say 4lbs of media or less) and are using crushed coral, you may need to stay at 6.6. That's about where I ran my smaller reactor. Really it's fine as long as there's not a slow steady drop in tank ph.

[Markster]

The reactor holds 5 lbs and it was shipped from the buyer (ebay auction) with media (crushed coral). I adjusted the C02 a bit to see if I can get the effluent pH up to 6.8. This was my first measurement of the effluent dkh so many more to do. Thanks.