uwphoto Posted January 15, 2016 Share Posted January 15, 2016 Have been hanging around for some time having just gotten back into SW. I have an interesting problem I need advice on regarding Ca++ levels. My set-up is a JBJ 45gal cube, Kessil 350W, ATO, RO/DI, SK45 Skimmer (soon to be replaced), Real Reef Rock. The tank is cycled, no algae etc. Using Red Sea test kits, my Calcium has been always less than 300ppm. This despite few corals and weekly 20% water changes. All other parameters are normal. I had the LFS (really a setup maintenance company I know) test my water (they use Red Sea test kits) and they got the same results, no recordable Ca++. Using my salt that I got from them, we mixed a fresh batch of seawater in the store, again no recordable Ca++. So I was given a new supply, the Ca++ measures 412 in freshly made water. My problem is that after 2 weeks of adding Ca++ (Calcion/Brightwell Aquatics) to my tank and two water changes (which I would not expect to make much of a dent in overall tank Ca++ ) I still can not get my calcium above 370. SpG 1026, Ph 8.1, PO4 .04, Mg++1320, KH 10.4, Ca++ 370 today. By the dosing instructions it would seem that I should have the system back to >400ppm. Do I just keep dosing until I get to my desired level? I am adding about 60ppm/day. Are there better additives? Pretty strong argument for testing all new batches of salt, something I never thought to do. How common is a bad batch of salt? Thanks for any suggestions. Link to comment
CronicReefer Posted January 15, 2016 Share Posted January 15, 2016 Bad bucketss are pretty rare as most companies test the salt batch themselves before distribution. I use Brightwell NeoMarine and have never had an issue so far. Just keep dosing daily, it will reach 400ppm. Link to comment
Beer Posted January 16, 2016 Share Posted January 16, 2016 Sometimes there are settling issues as the components have different weights and sometimes different particle sizes depending on how it was processed and mixed. Mixing the container (rolling the bucket or rocking the bag back and fourth to get the salt mixing around) periodically can help. Also if it was in a bag and got exposed to high moisture or humidity, some of the calcium can bind with carbonate and form calcium carbonate, which will be insoluable in the tank water, so your KH and calcium would be low. Can happen too if you add water to the salt instead of pouring salt into an agitating bucket of water. Have you been seeing the calcium slowly climb over the past two weeks, or did you get the initial rise and it has just been staying there? Link to comment
uwphoto Posted January 17, 2016 Author Share Posted January 17, 2016 With the faulty salt batch, I did mix the bucket and when opened new there was no sign of moisture. Anyway that bucket is gone. Nothing wrong with the new salt on all tests. The Ca++ with twice a day dosing did come up to ~370 ppm but seemed to plateau there. But, as a follow up I measured Mg, Ca, KH and repeated the tests at the LFS yesterday, (Red Sea and Salifert). My Mg is 1100 (My test kit Mg was a bit high compared to three other determinations). So I suspect my Ca will not normalize until I correct the Mg, which I am working on now. (Thankfully I am only dealing with a 45 gal cube. If I had used the bad batch of salt to start a >100 gal, what a PITA.) I wil post a f/up especially if I can't get back to normal numbers. Thanks for the responses. Link to comment
Beer Posted January 18, 2016 Share Posted January 18, 2016 Magnesium helps to prevent carbonate from binding with calcium. Basically it fills the sites on the calcium ions where the carbonate ions would bind to, preventing calcium carbonate formation, and consequently precipitating out. So raising the magnesium, to a certain point, allows a higher calcium concentration. At least that's how I understand it. I've never had a chemistry course, so I kind of pick things up as I go. Mostly from Randy Holmes-Farley's articles. Not being able to raise calcium makes more sense with Mg being at 1100 instead of 1320. You are hitting a saturation point with the magnesium that is allowing the carbonate to bind with calcium, causing it to precipitate out and not allowing the calcium to raise any further. It's awesome that you are getting things worked out. Sucks about the issues with the salt and Mg test kit though. I hope you are able to get the calcium back up after bumping up the magnesium. Link to comment
uwphoto Posted January 18, 2016 Author Share Posted January 18, 2016 Seems chemistry does work. Have Mg up to 1260 and Ca to 400. (Ph 8.1 and KH 9.2) But I have hit another plateau as these numbers have not changed in 24 hours despite additives ( not at the same time). I am checking Mg and Ca twice a day before adding elements and I separate the addition of Mg and Ca by several hours. Still the take home message for me is to check each new bag/bucket when mixed before adding it for the first time. Maybe I have had my one piece of bad new salt luck, but I don't trust any of them now. Link to comment
Beer Posted January 19, 2016 Share Posted January 19, 2016 I always test before doing my water changes. I've had issues with inconsistent parameters, small volumes are tough. I almost did a water change once without testing anything other than temperature, I was in a bit of a rush. Ended up testing and everything was insanely low. I had some pretty serious clumping in the bag due to really high humidity. Ended up mixing up a batch from a new bag. I thought the Ca and Mg bound up and wasn't dissolving. I realized a week later that I never tested salinity. I had mixed up a half gallon of water at one point and I think I left the 1/4 C measuring cup in the bag and mixed up a gallon thinking I added 1/2C of salt. I hate to think what could have potentially happened doing a 100% water change with half the required salt. Link to comment
uwphoto Posted January 20, 2016 Author Share Posted January 20, 2016 Finally have sea water. 530ml Ca++ added and 230ml Mg++ Ca++ 420. Mg++ 1380. Ph 8.1, KH 9.2, SPG 1026 All test frags doing well and Dartfish pair OK as well. Time to think about some coral... Link to comment
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