Montipora corals stressed

About a month ago I tore down my refugium in my sump and installed a new skimmer. Up until that point (2+ years) I have not had a skimmer on the tank. During that time I have had a few different corals added to the tank, and they did okay. The refugium consisted of a sand bed good sized LR that grew calerpa. The sand seemed to always have red slim build, and the tank had a high level of nitrates. In an effort to get a handle on the nutrient issues in the tank, I opted to install a skimmer. Also when I removed the refugium, any snails/crabs were placed in the MT.

My schedule of dosing has not changed in the last several months and the only change has been the removal of the refugium and the installation of the skimmer.

The last few weeks my montipora spongada went down hill fast. It is barely showing any signs of polyp extension, and the skeleton is basically white. Also I noticed a white spot on the tip of my tricolor acro, but other than that it looks fine. Along with that my orange montipora digitata is showing smaller polyps in a few places, and my superman montipora is now doing the same thing. Also I have an unknown acro that was green/bluegreen that is now brown and showing some signs of tissue recession. Also my strawberry shortcake frag is loosing color.

Aside from that my zoanthids, clam, gorgonians, and a few other SPS are looking good.

I checked parms Saturday and they all looked good.

pH 8.2
salinity 1.026
ammonia 0
nitrates 0
alk 9.5
cal 450
temp 76-78

Would adding a skimmer cause this to happen? I can only think that the skimmer is pulling so much stuff out of my tank that the corals are starving for what they want.

Do you happen to know what your mag level is?  I have heard that montiporas do well with high mag levels.  Don't know if it's a fact other than I keep my mag levels on the high side and my monti's grow like crazy.  Just a guess though.

Rich -

Bob-

When I tested for nitrates it was undetectable, but a few months back prior to adding the skimmer it was reading 25.

Yes I agree that removing the refugium is the likely issue, but why when all parameters look fine are things looking bad for a few of the corals.

The rock currently is in a holding tank until I get it sold. Also the sand that was in there is free to anyone wanting to come take it off my hands, and it is also in the holding tank.

I run carbon in a bag in the sump and change it out every month.

The red slim was in the sump only and not the main tank. I have plenty of flow in my tank, almost to much for LPS.

This is only my opinion based on my finite experience. As much as I think I know, I hardly know anything.

I'd say it was the drastic change in the filtration. Complete swapping out of an RDP Refugium for a Skimmer was a drastic change. Reefs don't handle drastic changes too well. It's going to take some time for things to get used to the new situation. It might have been good to run the skimmer on a schedule and slowly acclimate the system to the skimmer. Even now, turning off the skimmer could help the stressed coral to recover. I believe it would help to leave some crud (food) in the water. Who knows how much the Refugium was feeding the tank?

Montipora are the SPS we always recommend for beginners. The reason for that recommendation is that they seem to do better in a wider range of tank conditions. They seem to do better in what some hobbyists might call "dirtier" conditions, but which I would call an abundance of food. Nitrogen is a very important food.

If I were told I had to choose whether to use a Refugium or a Skimmer, and I could not use both, I would choose the Refugium. More types of coral will grow better in a system with an RDP Refugium. That said, there is no argument that a tank with a skimmer looks and grows different than a tank without a skimmer. Some people prefer the look, but I consider a skimmer to be supplemental filtration to a system that already has an RDP Refugium. The skimmer will remove crud, giving the biofiltration less to do, or looking at it another way, allowing the hobbyist to increase the bioload (more fish).

And when it comes to an RDP Refugium, just the other day RussianRick told me that swapping out the bioballs in his tank's sump for an RDP Refugium has had a very positive effect on his former FOWLR aquarium and it's nuisance algae problems.

One last thing I might as well say.  It seems to me that in this hobby there is way too much fretting over the N levels. Have you ever noticed how I NEVER ask for N levels? Most hobbyists think I'm crazy not to test for N but in my experience I have found that is not that important. What is important is to look at how the coral are doing, ignore the N levels and focus on Alk, Ca, biofiltration, water flow, lighting and Mg in that order.

Just my 2 cents.


Edited by Mark Peterson - September 13 2011 at 11:42am

Just so I am clear:

Mark, are you saying you think his Montis browned out because of a lack of nutrients in the water (adding a skimmer which removed too much good stuff), rather than they browned out because of excess nutrients in the water?

I'm saying it was the change in the entire system, including the nutrient levels. Some stuff disappeared. Some stuff increased in proportion.

As in the ocean, the environment of our aquariums has 1000's of variables. N is only one of those variables. P is another. That leaves 998 more. Most of those we cannot test and all of which we hardly understand. There are interactions between all those things too.

Algae eats things that a skimmer cannot remove. A skimmer removes things that algae cannot eat. AC removes things that neither algae nor skimmer can remove. Algae adds things to the water that coral and inverts like as well as adding things they don't like. Algae also provides a home for bugs that coral like to eat.

Have you tested phosphate?

Salinity is back to 1.023 and all of the corals look good now. The only issue is the spongoda is still looking bad, and one of the acros died.

Also I was able to put about 2 inches of sand below the skimmer. Since there is a large base and an inch between the sand, I think that I should be okay with it. Also I put about 2 inches in another compartment of the sump. Then I broke up the large LR and spread the pieces around in the sump. Right now I have more than I anticipated near the skimmer, but I think things should be okay. I will watch it and see.

Over all I think my issue really was the swing in the salinity.