High Alk but low Calcium

[finrod2]

I've been measuring with my hanna testers and getting consistent high Alk but low calcium. Any guess what could be the cause. I use a GEO calcium reactor.

Stats
240g with 100g sump
SG 1.022
NO3 .2
PO3 .00
PH 8.17
Alk 10.8dkH, 193ppm on hanna
Calc 335

I do have a refugium lighting running 24/7 and I've seen my PH creeping up from 7.95 to now 8.17. Not much experience on chemistry so not sure whats going on. I do have some coral but not enough to be stripping calcium. Any ideas?

 

[Maksimsf]

Test your Magnesium level. If your calcium ~335 your Mag may be ~1000 and needs to be somewhere around 1400 to support 400+ Ca.

 

[swcc]

yeah check mag...also...your salinity would be better at 1.024 -1.0265.

 

[finrod2]

Thanks guys. I dont have a mag test but have a friend that does.

 

[MarineSniper]

You'll want to watch your kh as you raise your ca, it will normally drop when the calcium rises. What type of salt are you using? 335 Ca sounds like standard IO

 

[Infiltrator]

And vice versa, raising alkalinity will lower calcium

 

[bertoni]

Dosing alkalinity and calcium won't affect the other parameters in any measurable way unless something is dosed well out of the recommended levels. I'd get a second opinion on the test kits before doing anything drastic, but the use of pH buffers can cause this type of situation, since they all add alkalinity, despite any advertising to the contrary.

I agree that getting a magnesium result might be interesting, but most often, the magnesium level in tanks is adequate, so I wouldn't count on that being the problem.

I agree that 1.0264 is a more natural level for saltwater, but making sure of your measuring device is important before making any changes. Calibration with a seawater standard can be very important.

 

[finrod2]

I'm using trop Marin salt. Could running my refugium lights 24/7 affect anything. My PH has gone up about .2 since I've added this lighting.

 

[bertoni]

The refugium lights won't change those parameters.