Where did the coraline go?

[jsr]

Okay, I will add as much information on my tank as passable. The tank has been up and running for a little over 4 months now. This is a 135g RR tank, 30g sump, no fuge, 4 x 140w VHO lights. This tank was up and running for 2 years before the skimmer leaked 15G of water onto the carpet, which had to be replaced. The tank was taken down and all rock (70 pounds) was placed in tubs for about 2 months. When I started the tank back, I added about 100 additional pounds and replaced the majority of the sand.

About 2 months in, the coraline was starting to take off. All was going well until 2 weeks ago when I started noticing the pinks and reds fading out. Here are the perams as of last night...

SG= 1.025
Nitrate= 0ppm
Nitrite= 0ppm
Ammonia= 0ppm
PH= 8.0
dKH= 9
Calcium= 420
Mag.= 1400
Temp.= 78-80

The only thing I noticed is that my KH and PH dropped about the same time as the coraline started fading. The readings were dKH of 6 and PH of 7.8. I added some KH buffer to my top off water and got it up to where it is now. Also, I changed two of my VHO bulbs about a week before the fading began. I replaced them with 12k 140w bulbs, the same that was in there before.

There are no fish/corals in the tank, only a small CUC that came from the old tank. This will be a FOWLR as I don't want corals at this time. I know that I don't need to be as vigilant on the calcium and mag, but I want the coraline to grow.

Anything stand out about why it is all fading away? I know the obvious would be the KH and PH drop but is there anything else?

James

[redfishsc]

Considering that you did not have anything other than a CUC in it, and your nitrates are 0, and assumedly have no other source of incoming nutrients, I suspect the corraline is starving. I believe corraline definitely has to have a source of nitrogen.


Your options would be obviously to either add fish, feed your CUC some table shrimp/fish food, or perhaps if you do not want any fish right now, CAREFULLY dose with potassium nitrate (Green Light brand Stump Remover, cheap at Wal Mart).

The dosing with KNO3 is probably the most technical, personally I'd toss in some hardy fish that you were planning on having anyhow.

[jsr]

Good point. I do add a cube of mysis every week just to keep the CUC fat and happy. I know the tank is healthy as the worms and pods are everywhere. I am wondering if the PH and dKH drop had anything to do with my coraline going south. The snails are covered with coraline, its just disappearing from the rocks and glass. Should I be looking at a chemical source, or do you think changing the bulbs would have that affect?

[kevin2000]

My 02

Coraline doesn't need much to grow ... calcium/alk and a bit of light. Most Coraline tend to prefer subdued lighting and its pretty common to see significant regression when you upgrade your lights .. perhaps your new bulbs had a similar negative impact?

[bertoni]

I agree that increased light levels could clobber the coralline. I've seen that in my own systems.

[redfishsc]

Wow. Even when just changing a couple of old 12K bulbs to a couple of new 12K bulbs? I would not have guessed that.

If that's the case, I'd assume the corraline would begin to regrow in short order, right?

[jsr]

Thanks for the replies. I will see what happens in a few weeks. I would have never thought the bulbs would really have that much impact.

[Randy Holmes-Farley]

Coralline often dies back substantially when a tank is first started. I know you said it was taking off, so that is probably not the case, but it is generally true that the coralline species that come in coating live rock do not end up being all the same species that thrive in the tank. Only a few will, and same colors and textures will be displaced by those that grow best.

Coralline takes a long time to get going well in many tanks. High phosphate and organics can deter it, as can low calcium, alkalinity, and magnesium.

[jsr]

Thanks Randy. I am going to lower the lighting schedule and test more frequently for the next few weeks and see if anything changes.

[Randy Holmes-Farley]

OK.

Good luck and let us know how it turns out. :)

[pusanpa]

If you have many small starfish then you won't have any.