Calcium not being used in mixed reef system

winland · 02/12/2010, 09:12 AM

I have not had to add any calcium supplement to my 150g mixed reef system, w/45g sump/refugium, in about a week. Calcium level is steady at 460ppm (API)
Other readings are...
pH 8.2
Alk 10.0
Mag 1400
Salinity 1.024

I do add alk on a daily basis (Randy's 2-part)

The test kit is good and my testing procedures are good because I have another mixed reef tank, 24g nano, that I test.

Corals are losing color and looking "pastel".

Suggestions???
Thanks.

Randy Holmes-Farley · 02/12/2010, 09:29 AM

What salt mix are you using?

Some have very high calcium, and water changes with them will help prop up calcium in some systems.

winland · 02/12/2010, 09:50 AM

I doubt that it is the salt mix. I use the same salt for both, 150g and 24g, systems
I do water changes in both systems on Saturday, 35g in the 150g and 4g in the 24g.
I try to keep my calcium at 450 - 460ppm in each system and I dose my water change water to that level prior to adding to the systems.
I add RO/DI water on a daily basis to topoff as needed.
I have done daily testing of calcium in the 150g system. It has stayed steady at 460 since the last water change. The smaller system is acting normally and does require daily supplement of calc/alk.
Both systems are independent of each other, no common plumbing.
Both systems get the same salt mix.
Both systems get the same RO/DI top off water.
Both systems get the same food and have similar mix of corals and fish.

Randy Holmes-Farley · 02/12/2010, 11:04 AM

How much alkalinity was added to the large system? We can easily calculate whet the calcium demand should be if alk is being used to make calcium carbonate by corals and such.

There are very few other ways to have substantial demand for alkalinity and not calcium.

I describe them here:

When Do Calcium and Alkalinity Demand Not Exactly Balance?
http://reefkeeping.com/issues/2004-12/rhf/index.htm

winland · 02/12/2010, 11:20 AM

I dose my 2-part in mid-morning.
On a daily basis, I have been adding 40ml of alkalinity supplement (baked baking soda mixed with RO/DI water) to keep my Alk at 10 dkh (Salifert test kit).
I will check out the link you provided.
Thank you.

Randy Holmes-Farley · 02/12/2010, 11:26 AM

40 mL of the alkalinity part (assuming it is my Recipe #1) to 150 gallons is the equivalent of 0.38 dKH per day.

If that is translated into the expected calcium drop, you'd expect 2.7 ppm per day if it was all used by corals to make calcium carbonate.

So the expected drop since last Saturday when you did a water change is about 16 ppm.

That might be within the precision of your calcium kit to detect.

winland · 02/12/2010, 11:38 AM

Thank you Randy,
I guess my problem is not really a problem at all. Just not a good enough test kit.

Thanks again.

Randy Holmes-Farley · 02/12/2010, 11:42 AM

You're welcome.

Good luck.

02/12/2010, 09:29 AM	#2
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 86,233	What salt mix are you using? Some have very high calcium, and water changes with them will help prop up calcium in some systems. __________________ Randy Holmes-Farley Current Tank Info: 120 mixed reef

02/12/2010, 11:04 AM	#4
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 86,233	How much alkalinity was added to the large system? We can easily calculate whet the calcium demand should be if alk is being used to make calcium carbonate by corals and such. There are very few other ways to have substantial demand for alkalinity and not calcium. I describe them here: When Do Calcium and Alkalinity Demand Not Exactly Balance? http://reefkeeping.com/issues/2004-12/rhf/index.htm __________________ Randy Holmes-Farley Current Tank Info: 120 mixed reef

02/12/2010, 11:26 AM	#6
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 86,233	40 mL of the alkalinity part (assuming it is my Recipe #1) to 150 gallons is the equivalent of 0.38 dKH per day. If that is translated into the expected calcium drop, you'd expect 2.7 ppm per day if it was all used by corals to make calcium carbonate. So the expected drop since last Saturday when you did a water change is about 16 ppm. That might be within the precision of your calcium kit to detect. __________________ Randy Holmes-Farley Current Tank Info: 120 mixed reef

02/12/2010, 11:42 AM	#8
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 86,233	You're welcome. Good luck. __________________ Randy Holmes-Farley Current Tank Info: 120 mixed reef

02/12/2010, 09:12 AM	#1
winland Registered Member Join Date: Jan 2007 Location: ohio 44883 Posts: 500	Calcium not being used in mixed reef system I have not had to add any calcium supplement to my 150g mixed reef system, w/45g sump/refugium, in about a week. Calcium level is steady at 460ppm (API) Other readings are... pH 8.2 Alk 10.0 Mag 1400 Salinity 1.024 I do add alk on a daily basis (Randy's 2-part) The test kit is good and my testing procedures are good because I have another mixed reef tank, 24g nano, that I test. Corals are losing color and looking "pastel". Suggestions??? Thanks.

02/12/2010, 09:50 AM	#3
winland Registered Member Join Date: Jan 2007 Location: ohio 44883 Posts: 500	I doubt that it is the salt mix. I use the same salt for both, 150g and 24g, systems I do water changes in both systems on Saturday, 35g in the 150g and 4g in the 24g. I try to keep my calcium at 450 - 460ppm in each system and I dose my water change water to that level prior to adding to the systems. I add RO/DI water on a daily basis to topoff as needed. I have done daily testing of calcium in the 150g system. It has stayed steady at 460 since the last water change. The smaller system is acting normally and does require daily supplement of calc/alk. Both systems are independent of each other, no common plumbing. Both systems get the same salt mix. Both systems get the same RO/DI top off water. Both systems get the same food and have similar mix of corals and fish.

02/12/2010, 11:20 AM	#5
winland Registered Member Join Date: Jan 2007 Location: ohio 44883 Posts: 500	I dose my 2-part in mid-morning. On a daily basis, I have been adding 40ml of alkalinity supplement (baked baking soda mixed with RO/DI water) to keep my Alk at 10 dkh (Salifert test kit). I will check out the link you provided. Thank you.

02/12/2010, 11:38 AM	#7
winland Registered Member Join Date: Jan 2007 Location: ohio 44883 Posts: 500	Thank you Randy, I guess my problem is not really a problem at all. Just not a good enough test kit. Thanks again.