Corals looking unhappy

[Elbereth]

My corals started looking unhappy a few days ago. First my Duncan, then my hammers and Cynarina, and today my torches aren't opening up as much as usual. I also noticed some new head growths aborted and tissue is receding on the hammer frags that was doing very well before this.

I'm practically a newbie and I only recently learnt about such crucial things as alkalinity. I know I had a big Alk swing but I fixed that almost two months ago and the corals were looking very good. Then I realized my Ca was low and I raised that. My levels aren't as stable as I would wish but definitely much better than they have in the past so I'm not sure what's wrong. (I should also mention I have my macroalgae in the same tank in case that's relevant because I think I remember reading that macro can cause a pH swing at night? I keep meaning to plumb in a separate sump/refugium so I could run a reverse light period but I haven't had been able to start on that because of real life.)

My (known) parameters are:
pH: 8.2
Nitrate: 0
Alk: 7.5
Ca: 340
* I know Ca is a bit low - I'm currently raising it with CaCl. And I'm waiting for my Mg test kit and additive to arrive.

The only thing I can think of that I changed recently is that I added some sand from a QT tank after boiling it for a few hours to sterilize. I rinsed it well but not in RO water and it was damp when I added it so perhaps heavy metals or something from my water source? I know it's a long shot but that's the only thing I can think of that changed recently.

I know it's very hard to diagnose without measuring more parameters but maybe you folks could list off the top likely factors that could cause such an issue? I've been doing some reading but nothing has rung a bell unless it is an alk issue. I wonder if there's something glaring I just don't know about because I'm such a noob.

Thanks in advance!

 

[Idoc]

Alkalinity is a little low for LPS, but if stable around that, they adapt.

Calcium too low.

LPS like some nutrients in the tank...ie: no3 and po4. You don't mention po4 levels. I'd raise nutrients a bit and see if that perks them up.

 

[Klyle]

I was thinking the same thing. You may be filtering too well. No3 is coral food. They need small amounts. I run a mixed reef around 5-10 ppm No3. In a perfect world (for me) No3 is about 5

 

[Elbereth]

Thank you both for responding.

I know about the nitrates. I feed a little; I suppose I should feed more.
But would low nitrates Ca cause such a sudden change though? They were looking just fine four or five days ago.

I'll measure phosphate when I get a chance but I assume it's very low as well.

 

[vetteguy53081]

moderate light and water flow
Temp 77-79
ph 8.1-8.3
salinity 1.025
nitrate < .5
phos < .04
Ammonia < .03
mG 1300
Alk 8-9
CA 440

 

[Tired]

Low nutrients can cause what looks like a sudden change, yes. Corals take awhile to react to things, so you can have a situation where they're quietly suffering, but don't show it until they hit a certain point and start visibly dying. This can also mean that they may take awhile to visibly react to a positive change, unfortunately.

I would disagree with the nutrient levels suggested above. They work just fine for some tanks, but for a person newer to the hobby, I'd say err on the side of more nutrients. Low nutrients are much more likely to cause harm than high nutrients. I would say try for around 5ppm nitrates, maybe a little higher, and no less than 0.03 phosphates. Do a water change right now, in case there's contaminants from the sand, then stop doing water changes altogether until your nutrients are much higher.

Do you feed the corals? If not, start feeding them. Turn the pumps off and put the food directly on them for them to eat, so it's not blowing randomly around the tank getting into crevices.

 

[Salty Rambler]

You mentioned adding sand that was previously used in a QT. Did that QT have any copper at any point?

 

[stevewright1]

I would consider adding a Polyfiter pad to your set up if you do suspect your water supply for sand washing was possibly the issue/ cause.
there also other products available that will remove heavy metals , I just mention the product I am most familiar with.

 

[Elbereth]

Thank you for such a good explanation Tired! Now that makes more sense. I'll try as you suggested.

I feed the tank and corals every 2-3 days. No copper in the QT. I'll see if I can get some Poly Filter. Thanks for the suggestion!

 

[Elbereth]

I fed all the corals last night and they're already looking better. Also raised Ca to 385. I guess I must've skipped more feedings than I thought recently so the corals were starving.