Out of the blue my calcium has completely dropped out. My Reefer 170 tank is full of sps and I have maintained a slightly high level of calcium about 460/480 for several years and maintain my alk at about 7.8/8.0 and mag about 1300/1400. About 5 weeks ago I changed from kalkwasser drip + TM AFR to a hybrid Bolus addition using Sodium Bicarbonate + TM A- elements and Calcium Chloride both made up to RHF recipes. Everything was going great for the first few weeks (my corals never looked better). When doing my weekly calcium test the calcium has suddenly dropped to about 100 (0.1 ml used to turn the solution blue using a Salifert test kit) I'm currently adding about 5 times as much Calcium Chloride solution daily (now a 100ml daily of RHF recipe Calcium Chloride) and am seeing no increase in the calcium level testing daily. I am not seeing any precipitation when the calcium is added to my sump via my doser. Thinking my test kit was out I made up some fresh TMPR salt which measured 440ppm, so a faulty test kit is not the problem. This problem has been going on for over a week now and although I am not seeing and real deterioration in my corals, the polyp extension is still good, the colours are not as good as normal. Scratching my head at the moment, has anyone any ideas how to correct this problem.
Sudden calcium level drop
- Thread starter yorky1
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Im a little confused by your decision that 0.1mm was the amount used to go blue. When you first add the Ca-2 liquid from the syringe, you add 0.6mm leaving 0.4mm in the syringe to begin the drop by drop process. That's starting at 310 and only goes up from there. I assume I misunderstand what you said.
Randy Holmes-Farley
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It is very unlikely that calcium can get to 100 ppm in a reef tank. So despite the discounting of a test issue , I still think that likely. Salifert periodically changes their kit, so be sure you are using directions matching your kit version.
That said, can you describe exactly how you are mixing up the two part?
Alkalinity: I dissolve 82g of food grade Sodium Bicarbonate in about 800ml of warm RO/DI water. I then add 30ml of Tropic Marin A- elements then make up to 1litre when dissolved.
Calcium: I add 72g of Calcium Chloride to about 800ml of RO/DI water then make up to 1 litre when dissolved.
I had been adding 60ml of alkalinity (one shot bolus) and 20ml of calcium added during the light cycle in 10 x 2ml doses to maintain 7.8/8.0dkh and 400/420 ppm calcium. I follow the Salifert directions to the letter, but, when I add 0.6ml titrant (as per the instructions) the solution immediately goes dark blue and in subsequent testing the solution goes blue after about 0.1ml of titrant added. I will purchase a new test kit just in case it is faulty but as I mentioned in my earlier post a new batch of TMPR salt water tested correctly. I also will send off an IPC sample ASAP.
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I’ll double check the recipe later, but that amount does not mean 100 ppm, but something less than the chart entry for 0.6 mL added/0.4 mL remaining.
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Recipe is a little short on bicarbonate, IMO, but not by too much, and that doesn’t explain your calcium issues. I give a recipe here;
An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System by Randy Holmes-Farley - Reefkeeping.com
An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System by Randy Holmes-Farley - Reefkeeping.com
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Why are you adding so little of the calcium part? That recipe is close to 1:1.
When the problem first arose I added 0.6ml of Ca2 as normal but instead of developing the usual pink colour the solution immediately turned a deep blue colour. I retested but only added 0.1ml of Ca2 which turned a pale blue/grey colour similar to the normal end point. Repeated tests give the same result.
I only added the smaller amount to slowly drop the Calcium from the 450/460ppm (when using kalkwasser +TM AFR) down to 400/420. I was testing Calcium daily, whilst reducing the Calcium level, when I encountered the sudden drop from 410 to somewhere about 100 in 24 hours.
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Randy Holmes-Farley
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But that 100 ppm is not the correct interpretation of the test result.
The salifert kit will not work properly if you only start at 0.1mm. The initial add of ca-2 has to be somewhere around 0.5 - 0.6mm. If you get blue immediately at 0.6mm, you'll be somewhere near 300. back off on the initial amount to something closer to 0.5mm so you will get the pink color first.
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