Low alkalinity and calcium

[gostby88]

I have a 13.5g tank that’s been set up for about two months. Two weeks ago I added my first three frags: a duncan, xenia, and gsp which are all doing great. A couple days ago I got five more frags, and all are doing good except for a frogspawn and candy cane which haven’t opened. I tested my water today and noticed my alk was low at 7 and my calc was low at 360. Alk is usually at 8-9 and calc is usually 400-420. My ph is stable sitting around 7.9-8. I already dose alk weekly but am wondering if I should start dosing calc as well. Are the added corals the reason my levels are depleting?

My other params are:
Salinity: 1.025
Ammonia: 0
Nitrites: 0
Nitrates: 5
ph: 7.9-8
Phosphate: 0.03

 

[vetteguy53081]

I have a 13.5g tank that’s been set up for about two months. Two weeks ago I added my first three frags: a duncan, xenia, and gsp which are all doing great. A couple days ago I got five more frags, and all are doing good except for a frogspawn and candy cane which haven’t opened. I tested my water today and noticed my alk was low at 7 and my calc was low at 360. Alk is usually at 8-9 and calc is usually 400-420. My ph is stable sitting around 7.9-8. I already dose alk weekly but am wondering if I should start dosing calc as well. Are the added corals the reason my levels are depleting?

My other params are:
Salinity: 1.025
Ammonia: 0
Nitrites: 0
Nitrates: 5
ph: 7.9-8
Phosphate: 0.03

Not sure what test kits you’re using but numbers may be false.
Additionally, if you’re doing regular water changes, your levels should be in range without additional dosing.
Are you able to take a water sample to a trusted LFS that does Not use API test kits and see what readings they come up with and to compare with yours?
Hammers can suffer with calcium levels below 380 but also from too much light or water flow
Cand cane- moderate light and water flow

 

[nereefpat]

I tested my water today and noticed my alk was low at 7 and my calc was low at 360.

Just FYI, alk of 7 is about natural seawater. I like to see Ca at 380-450, but keep in mind Ca test kits are +/- 20ppm.

I already dose alk weekly but am wondering if I should start dosing calc as well. Are the added corals the reason my levels are depleting?

Generally, yes, if you dose alk you should dose Ca. Corals are using alk. Coraline algae is a big alk sink as well. Abiotic precipitation accounts for a little bit too.

 

[Lavey29]

I agree, water changes are all that is needed on a light stock nano tank to keep numbers stabil.