Maintaining Alk


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Apr 22, 2021
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London, ON, Canada
Hi Everyone,

I need some insight and advice. Three months ago my Alk was 6.1 (Hanna Checker test kit) and Cal was 380. I began dosing 110 ml of Alk and almost 200 ml of Cal daily. I couldn't seem to keep my parameters up. I heard that Mag could be the problem so I tested my Mag and it was at 1050. I went through 1 kg of Nyos Magnesium in the last 6 weeks trying to bring up my Mag. It's now at 1365. I still have to dose 100 ml of Alk and 130 ml of Cal daily to keep my parameters up. I have a small 3" green goddess, a rosta that has 6 heads and a large colony of pulsing xenia. I do water changes every 2 -3 weeks with high Fritz Alk salt (was using coralife before this). Is this normal to be using this much Alk, Cal and Mag for a tank that is 6 months old?




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Feb 14, 2019
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Mag should be ideally where your salt mixes. Typically that's 1200-1300.

Mag is only consumed when calcium is consumed, so without even testing you can get a pretty good idea if your mag is down if you've had to dose a lot of calcium.

I recently wasnt paying attention because I hate testing mag and let it get down to 1000 in my main SPS tank. It didn't affect anything, but the problem is bringing it back up too fast can cause SPS to slow down as they re acclimate. So, you don't want mag to get to low. To get around my laziness I've started mixing magnesium in with my calcium chloride jar although there is some debate on the exact ratio.
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