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Alkalinity Consumption Ridiculous

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  • Alkalinity Consumption Ridiculous

    Hello All,
    I have never posted here before but have been a member for a year now. I have been struggling with a tank with an incredible alk consumption issue. I have 80 gallon total water volume and have about 8 corals most of frag size and one 3-4inch derasa clam. My tank has been running over 1.5 years now and for the last 6 months I have more then struggled with dkh (using a Hanna tester). The problem appears that the more alk I add the more the tank consumes. I use a Kalk reactor on a perstaltic pump as well as 2 part b-ionic. I had gotten as high as all my top off with the kalk (3500ml) and 110ml of each part of 2 part but that is ridiculous. I tried large volume water changes and did essentially 3 of those with no affect on the alk consumption. The alk would spike to the level of the water mixed and drop over days back down. My mag is 1310 and calcium runs 415ish. Nitrates and phosphate at 0. I had some precipitation prior but currently have none and do not understand why this tank consumes an incredible amout of alk and the more alk I add the more it consumes. I scrapped all the coralline I could reach and currently do not have a large amount. Currently I have backed off to 1000 ml of Kalk and 10 of each of 2 part. My alk this morening is 6.0. Iím extremely frustrated. Attached is a graph of my dkh.

    Any thoughts?


  • #2
    What is your target alkalinity? Are you dosing anything to keep your nutrients down? Are your corals growing? What is your ph?

    I ask because I was in a similar situation a few months ago. I had an extremely difficult time getting alkalinity up in my tank and was at one point dosing 72 ml per day of esv on 50 total gallons volume and not seeing any real growth to accompany it. I too was at zero nitrates and phosphates. I decided to try going away from the ulns approach and dosed some nitrates to bring the number up. I was still at zero phosphates which led to a bout of dinoflagellates. I dosed phosphates to get a readable number.

    Once I was able to get readings of both nitrates and phosphates a few interesting things started happening.
    1. My dinos receded and have disappeared
    2. My ph increased. I had been hovering around 7.7 and now it's up around 8
    3. My alkalinity started to climb going from about 8.4 to 10.3 over a few weeks. All the while I was turning back the dosing. As of yesterday I'm now dosing 8 ml per day while the alk is slowly falling.
    4. My corals look better and happier than I've ever seen before. Sps that was healthy but not growing is now showing signs of encrusting. A duncan that was previously just kinda there has the beginnings of two new heads.

    I can't for sure say that nutrients are the only thing that caused all of this but I think that algae growth is an important biological factor in reef tanks and the ph effect that they contribute is an important part of the chemical process we need.


    • #3
      About 6 motnhs ago I was dosing 130ml of each per day in my tank, but I could never get my Calcium to raise, I then found out it was a combination of not enough magnesium to buffer and a lot of extra that was just percipitating out. I now dose 20 ml of each per day. I never thought it logical to think I was dosing too much to keep my levels where I wanted, i'd add 10 ml more per day one week and again and again. But hopefully that helps.