Photo inhibition

I wonder if I should slowly change out the water and mix my own salt with distilled water. maybe there is something else in the water causing my problem?

 

Since you have ruled out almost everything else, I would say yes to making your own water. Or even better, buy yourself a new RO/DI unit and stop buying water

 

Sure seems like it.

I just don't know what in the water could be affecting growth, but not the overall health of the coral. That's why I never considered the water. Everything I tested for checked out and nothing ever dies or looks bad. Things retain PE and don't bleach. You can see in the images that the SPS look healthy.

I have considered a RODI, but with a 20 gallon system, it's been just as easy for me to buy water. Not a huge expense. With my 55 in the works, a RODI unit makes more sense.

 

My best guess after reading this would be that parameters are not as stable as you think. It could be something as simple as a slight sg change with top offs. Especially with a small water volume. Next guess would be alk. If that varies much at all, your SPS will still look ok, but stop growth. Your lighting looks fine, but what is that dying coral, the one that looks like a favia or chalice?

 

I don't top off. I have an ATS and every time I check (weekly) my salinity with my calibrated refractometer, it reads 1.025.

Alk never drops (not surprising since nothing grows). I check this using a Hanna Checker and a Red Sea kit.

The coral dying was flipped upside down in the sand for a month (happened 2-3 times, actually) and largely contributed to its death.

My SPS actually grew better before I had my sump, believe it or not.

 

I'd say bump up your sg slightly. I do better at 26 to 27. There are also more elements in the water at higher sg. I notice slowed growth when ca gets down to 400 and alk under 8.

You seem to know what is right. Most likely something as not as it seems.

 

I think I am going to change out my water with my own mix and bump up the SG in the process.

My calc. is 450 and my alk. is about 10.

You are right, something is out of whack and I can't seem to pinpoint it, no mater what I do. It's softies and LPS too that are stunted. That's what has me scratching my head.

 

I would do the salt, as well. Keep it under your control.

With 1.027 sg I like ca to be 440 and alk to be 9. My biggest improvement over the last year was calibrating my refracto. Silly, but it took a few years to realize the importance. Every other measurement is off if sg is not correct.

 

Looking at the pics you posted, I feel your polyps actually look unhappy in several shots. I've seen that before; when my corals deteriorated under my LEDs. When I switched, new healthy frags took off, but most of the unhappy corals took a really long time to recover.

My simplification goes like this. Corals have a rechargeable battery. They can do well and look great for a while in bad conditions by drawing down the battery. Once that happens however, they only start growing again when it's fully charged.

I think you need to change nothing, keep everything as constant as possible, and wait it out. I've been there. I sucks staring at them daily wishing they grow. Keep it as consistent as possible and wait it out.

Mix you own saltwater. Unrelated to your problem, but good advice nonetheless.

 

I just invested in one myself in the spring after 3 years of not using one.

Come to think of it, I had better success when I was using my own salt w/ distilled water.

Even worse, I had a lot of success using tap water when I started 3 years ago. Algae issues, but good growth.