Help with parameters/corals

jake760 · 2026-08-14T10:33:48-0400

Alittle backstory to start… tank is a fluval evo 13.5 and is about 7 months old, I have 3 fish pink streak wrasse, bangaii cardinal, and a yellow line cleaner goby. Light is an ai grow blade (attached scheduled), flow is a Nero 3 on pretty low settings but random flow, and an rfg on the return. I do have a small fan blowing across the surface to help deal with this heat wave.

With that being said I’m having a problem where about halfway through the day in the late afternoon my corals start to close up after looking good for the first half of the day. This has been happening for about a week or two, I noticed it once I added the fan on top but not too sure with the direct correlation. Typically I feed frozen mysis once a day, sometimes I’ll throw in some tdo pellets at random times, and reef roids or benereef once a week.

Corals include: 4 torches, 4 hammers, 1 frogspawn, 2 acans, 1 trumpet, 2 gonipora, 1 duncan (very unhappy), 4 mushrooms, 6 zoanthids, 4 leathers. I think that’s everything

Maintenance: change filter floss about once or twice a week and about a 1-2 gallon water change every week

Parameters:
Alkalinity- ~ 6.1 (salifert)
Phosphate- .058 (Hannah phosphorus ulr)
Calcium- ~400 (salifert)
Nitrate- ~5ppm (salifert)
Temp- 80f

I think I listed all the information available if more information helps let me know I’ll try and get it. Any and all advice/ help is much appreciated thank you!!

Gumbies R Us · 2026-08-14T10:36:03-0400

Are you doing anything to dose for alk? That is low; it needs to be 8dKH or higher

What kind of flow are your corals getting?
Photos?

ReeferTCG · 2026-08-14T10:40:15-0400

Do you have an ATO?

jake760 · 2026-08-14T10:41:29-0400

Not doing anything to dose alk but it may be time to start. It has always been between 6.5 and 7 on this tank. Last water change was a week ago. Flow is pretty good I don’t have a picture of the corals closed I can try and get some later the lights aren’t on yet.

jake760 · 2026-08-14T10:41:47-0400

ReeferTCG said:
Do you have an ATO?

Yes I do salinity is good forgot to list that

jake760 · 2026-08-14T10:47:53-0400

Gumbies R Us said:
Are you doing anything to dose for alk? That is low; it needs to be 8dKH or higher

What kind of flow are your corals getting?
Photos?

The Nero 3 is on random between 3 and 8 percent on high variance if I turn it up too high sand starts to blow around. And the return is an axis 20 on 48 percent with an rfg.

Mr. Mojo Rising · 2026-08-14T10:55:45-0400

IMO you have a very short peak period, your light I believe is only 20 watts, IMO a little underpowered. I would turn the light up and give it a longer peak, My tanks get 11 hours peak.

allof fish · 2026-08-14T10:57:12-0400

I would definitely say low alk is your issue. Try to raise it up to around 8 and keep it there

jake760 · 2026-08-14T10:59:45-0400

Mr. Mojo Rising said:
IMO you have a very short peak period, your light I believe is only 20 watts, IMO a little underpowered. I would turn the light up and give it a longer peak, My tanks get 11 hours peak.

My light was on slightly lower settings a couple of months ago and they never closed up like this. I turned it up a few months ago and now they are closing the past couple weeks shortly after the peak photoperiod. I could make the peak longer for sure I see what your saying

jake760 · 2026-08-14T11:04:43-0400

What would you recommend to raise alkalinity? I have these 2 they are a couple years old from my last tank before I moved but I don’t think they expire. I probably wouldn’t need to add any of the calcium bottle but is this a good one to use here?

Randy Holmes-Farley · 2026-08-14T11:10:55-0400

jake760 said:
What would you recommend to raise alkalinity? I have these 2 they are a couple years old from my last tank before I moved but I don’t think they expire. I probably wouldn’t need to add any of the calcium bottle but is this a good one to use here?

Those are ok, but just keep in mind they are not properly designed for 1:1 dosing, despite the claim. It’s an unusually simple thing that Seachem got wrong.

Randy Holmes-Farley · 2026-08-14T11:12:58-0400

I’m not sure what the problem is for the corals closing up. Excessive light is the one thing that could cause closing part way through the light cycle. I don’t see why low light or low alk would do that.

jake760 · 2026-08-14T11:14:37-0400

Randy Holmes-Farley said:
Those are ok, but just keep in mind they are not properly designed for 1:1 dosing, despite the claim. It’s an unusually simple thing that Seachem got wrong.

Got it, what would you recommend to raise alk? Trying to keep it somewhat simple but I understand it’s not the simplest thing.

jake760 · 2026-08-14T11:17:48-0400

Everything was fine when I had the light alittle lower except I my zoas were reaching. I suppose I could start with going back to running the light on the lps grow at 60 percent like I was before to see if that changes anything.