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melev

Alkalinity Swing

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I recently had an alkalinity swing creep up on my reef. Normally I like to keep the tank around 8 dKH, and yesterday I noticed the duncans in my frag tank (part of the same system) were closed up. One bad habit I've developed over the years is to watch the corals for indication of problems instead of water tests each Saturday like I used to perform. I need to get better about that. I did a quick check with my Elos Alkalinity test kit and was shocked when it hit 21 dKH. So I tested again, and it measured 19 dKH. Safe to assume it was about 20, way too high.


I turned off the calcium reactor's output immediately, and let the solution within the body of the reactor recirculate so it didn't stagnate. Today I did another test and the reef measures 18 dKH. Since the number is quite high, I don't want to pull it down quickly and shock the SPS corals. I'm thinking I'll bring it down to 15 dKH, then let the tank idle at that amount for about a week, then bring it down to 11 dKH and let it idle for a week.


The idea is to get that number back within line without losing corals in the process. Bringing it all the way back to 8 dKH now would definitely kill some colonies. Just wanted to share my thoughts with y'all, and I'll be sure to post an update in the future.

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Looking at the system, the corals really look normal. The anemones are fluffy, the LPS are open. Even that Duncan colony from yesterday that looked closed up looked totally fine today.

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So what caused this number to rise? The only thing I can think of is that I cleaned out and refilled the calcium reactor with fresh media. I didn't change the pH level within the reactor, which is set to 7.0. I'm going to find the manual to change it to 7.5 now, so the solution coming out of the reactor will be less alkaline. (Hope that's the right term)

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  1. evoXmr's Avatar
    I noticed that mine changed recently and it was due to changing up the flow to my various reactors. It caused the pressure going to the calcium reactor to change, which was enough to change the output even though the output valve of the reactor stayed the same. Maybe that new pump you installed a while back changed your flow? Just a thought... Everything looks amazing! I am so glad you posted that new video with just your tank on display. I used a few times while on vacation to show people what I want mine to look like someday!
  2. melev's Avatar
    That's an interesting thought. I watch the output, mostly. I think in full bag of new media (4 kg I think) was way more potent than 2" of old mush. Today the tank measured 15 dKH and I've resumed the calcium reactor to stabilize it for a few days at this level to avoid letting it drop down more... I want to bring it down gradually so the corals don't take a hit. Hopefully.
  3. brotherd's Avatar
    Marc how is your alk level now?I'm using the same reactor but in the original configuration with a feed pump in the sump. I think I agree with evoXmr regarding the increased effluent output.I wonder how much more co2 was used during that period to raise the alk that high?
  4. melev's Avatar
    I tested last night, and the reef is at 15 dKH. I dosed 1-gallon of Magnesium into the reef yesterday over a 6-hour period because it was low. Calcium measured 450ppm.

    It wasn't more gas that raised it. I think it was simply the amount of media I added after I cleaned it out. It was apparently super potent, and I didn't test it weekly like I should have. I never have, but I think I will in the future.
  5. brotherd's Avatar
    A gallon of mag! Wow! That's something I haven't tested for in a long time. How much did that raise the level?I guess it sounds like a lot to me but I remind myself that your system is huge so it probably isn't that much?
  6. brotherd's Avatar
    Just remembered to ask you if you got the qd's set up for the mp60's yet? I'm thinking of them but the Canadian $ sucks at the moment so...
  7. melev's Avatar
    Quote Originally Posted by brotherd
    A gallon of mag! Wow! That's something I haven't tested for in a long time. How much did that raise the level?I guess it sounds like a lot to me but I remind myself that your system is huge so it probably isn't that much?
    It was at 1200ppm. I need to test today and see where it is, but I like it closer to 1400ppm.
  8. melev's Avatar
    Quote Originally Posted by brotherd
    Just remembered to ask you if you got the qd's set up for the mp60's yet? I'm thinking of them but the Canadian $ sucks at the moment so...
    I installed one of two QD drivers on the MP60s.
  9. melev's Avatar
    Magnesium tested today at 1300ppm. So a gallon wasn't enough - I need another one. hehe
    Alkalinity is at 14 dKH.
    Updated 09-02-2015 at 01:54 PM by melev