problems getting calcium up

[RDCompton03]

I am working with a six month old set up and really cant be happier with the results so far especially as my water params are concerned. The tank is mostly a mixture of soft and LPS corals and all seem to be doing well and growing with the exception of a trumpet which in hindsight may have been on the decline when i got it. My only issue seems to be that I cant get my calcium levels up. Even though I have been dosing regularly with a two part I am at about 380 today down from a high of 420. My original target was to get close to 450. Initially I dosed with kalk and magnesium but went to the two part because it was easier. Have had the same issue with Mg only able to get it up to about 1050.

My other params are

Ammonia 0
Nitrites 0
Nitrates 0
Phos 0

Salinity 1.26
Alka 9
Ph 8

After todays water tests I have decided to go back to kalk dosing hoping for better results . I have a 40 gallon tank. With patches of coralline algae the size of a dime is it possible that that much calcium is being sucked out of the system? I certainly welcome any ideas or thoughts that anyone has and recommendations on where I should go with the problem,,,,or is there a problem??? By the way I am using a Salifert test kit for calcium and Mg

[Coralreefer1]

I wouldn't think that a small amount of corraline would be responsible for depleting your calcium level. Usually if you have a low calcium level, your Alk level is very high, but this isn't the case with you. I like dosing with Kalk and have been doing it for years with continued success. Without spending money on a calcium reactor, Kalk should be ok for you. Frequent water changes will also help to elevate levels, while reducing detritus, contaminates and particulate matter. Dose magnesium supp. or Epsom salt so that your magnesium levels are roughly 3x what your calcium level is as a rule of thumb.
Good luck!

[ericarenee]

how much surface gas exchange do you have on the top of the water?
Are you using a sump/ Skimmer?
how much Evaporation do you have and do you have a ato?

[RDCompton03]

I probably have minimum gas exchange on top of the water. There is no real agitation at the top of the DT however I do have a sump stocked with cheato. There is moderate exchange there primarily from the DT supply. In my initial set up I had a skimmer but during the cycle decided to go a different direction and remove the skimmer. I know this is a controversial topic but after running my last system with a skimmer and always struggling with params I decided to give it a try. So far I am very pleased with that as well as my bare bottom DT. I have about 3/4 of a gallon a day of evap and have my ATO on order should be here this week.

[DSMpunk]

You need to get you Mg up to snuff or you will continue to see your Ca levels dropping. It's a somewhat complicated reason, but the solution (heh) is simple.

Once you get your Mg up to 1200+ then you should be able to add more Ca without it precipitating out as calcium carbonate.

http://www.advancedaquarist.com/2003/10/chemistry

To find out how much Mg you need to get to that level, use this calculator. You may need way more than you think. Just remember to go slow.

http://reef.diesyst.com/chemcalc/chem_calc3.html

[ZeeSparrow]

You need to get you Mg up to snuff or you will continue to see your Ca levels dropping. It's a somewhat complicated reason, but the solution (heh) is simple.

Once you get your Mg up to 1200+ then you should be able to add more Ca without it precipitating out as calcium carbonate.

http://www.advancedaquarist.com/2003/10/chemistry

To find out how much Mg you need to get to that level, use this calculator. You may need way more than you think. Just remember to go slow.

http://reef.diesyst.com/chemcalc/chem_calc3.html

+1 You need to get Mg up first. Raise Mg, then Ca, waiting at least 8 hours between dosing (don't add them both at the same time). Once you get your levels where you want them, you can use kalk again to maintain. Kalk doesn't do much to raise but is great for maintaining.