Pale corals due to carbon dosing?

[Conceyted]

I have been in the hobby for nearly 10 years and our 29 gallon biocube has been set up for nearly two years. The tank is very stable, but it did go through the standard early algae cycles of cyano and diatoms. I was able to successfully tackle each with some good husbandry, but then hair algae came along. At first I did the usual tear and siphon out between water changes but it only got worse. Eventually it progressed to me almost tearing down this tank before finally reading a philosophy someone posted here on RC; Try everything you can rather than one thing at a time. If it gets fixed it isn't really important what fixed it as much as it is important that it got fixed. I took this approach and started doing daily siphoning and water changing, constant changing out of media (carbon/gfo) and filter pads, target dosing peroxide directly onto the algae spots, and finally I began vinegar dosing. I followed the guidelines on vinegar dosing that I had found in the Reef Chemistry forum and between my very aggressive manual removal methods, a 3 day blackout, and my dosing, the hair algae I had dealt with for nearly 6 months finally came under control.

One day about three or so months ago I remember looking at my tank which was completely algae free and feeling as though I had succeeded. Ever since I have maintained a somewhat small level of vinegar dosing and I decided to keep dosing peroxide, as well. About 2 months ago I started to focus my attention on something else, since the algae had been conquered. My corals just didn't look colorful. My tank is a mix of things from monti caps and setosa to frogspawn and torches. The corals had once had some great color and even with the hair algae overrunning the tank the coral growth I witnessed was incredible. Lately, though, the corals look pale. Ever since I began aggressively attacking the hair algae my corals have not been colorful. I made a decision to stop vinegar and peroxide dosing and within two weeks of doing so I had some hair algae growing in the sand again, but my corals showed signs of color. I let it go longer and the hair grew longer, but never did grow on the rocks. I did a manual siphon during a scheduled bi-weekly water change but the hair came back. I decided that I had to start dosing vinegar again, which I did, and the hair stopped growing. I repeated this stopping of dosing again and the same thing occurred, corals colored up slightly but hair began to grow once again and only in the sand. At this point I decided that I had no choice but to keep dosing, but I have suspicions about my sand and what might be in it that is causing hair algae to grow.

So I started to try to figure out why this might be occurring. My gut tells me the sand has absorbed some form of nutrients which is it leeching back into the tank and causing the algae growth. I have not read anything to indicate that vinegar dosing can cause paleness in corals, but I think a lack of nutrients in the water can cause this and organic carbon dosing does seem to absorb nutrients, so this theory of mine does make sense.

Do you think I am on the right track if I stop dosing vinegar and try slowly pulling the sand out of my tank? Eventually if I could get to the point where my tank had no sand left and I could stop dosing vinegar I think that I could get my corals to color up and then re-add a layer of sand.

Thank you for reading the book I wrote above :beachbum: and for any help you are able to give.

Adding some additional information I know people will ask:

- RODI outputs 3 TDS from RO membrance and 0 TDS after the dual stage DI cartridges I am running.
- Parameters on the tank are:
Ammonia, Nitrate, Phos are all undetectable/0
pH 8.2-8.4
480-500 Calcium
8.4-8.7 dKH Alkalinity
1600 Magnesium
- My photoperiod is 10 hours of blue led lights which have a ramp up and ramp down of about an hour each way and 6.5 hours of white leds. I am running around 40 watts of white LEDs over the tank and around 60 watts of blue LEDs.
- My bioload is as follows: pair of ocellaris clowns, 1 royal gramma, 1 pygmy angel, and a sixline wrasse.
- I feed once every two days but have started doing daily feeding and heavy feedings to try to increase nutrient levels.

 

[Allmost]

your proposal does make sense.

I personally would start siphoning the sand weekly [if not toooo deep, if its deep, then siphon the top], continue vinegar dosing, and feed the corals more....

 

[Conceyted]

your proposal does make sense.

I personally would start siphoning the sand weekly [if not toooo deep, if its deep, then siphon the top], continue vinegar dosing, and feed the corals more....

Well, if I continue vinegar dosing I don't need to siphon the sand ever because the hair never grows. Or do you mean I should begin to remove the sand but still continuing to dose vinegar while I do so?

Would increasing my bioload by adding more fish be a bad idea? That would feed my corals.

 

[oscarinw]

Your situation is quite interesting. I have read somewhere that some types of sand tend to leach phosphates on to the water column. However, you haven't mentioned any parameters which makes me want to start from the beginning... Do you see a climb on your Phosphates and Nitrates when you stop dosing? Also, has your feeding regimen changed lately? How about lights?
On a 2 year old 29 cube, I don't think it would be unrealistic to experience an buildup of nutrients inside your sandbed.
I would try to stir up and vacuum the sand as deep as you can right before water changes and also do a couple or 3 major water changes. Maybe in the 15-20 gal. range for your size tank. Additionally, check the TDS reading of your makeup water and see if your problem might be there.
Adding an under the gravel CUC might also be benefitial.
I know I have given you everything but a concise idea but I don't necesarily think that you can achieve much with a sandbed replacement necesarily. It might make things worse for all we know.

Good luck with things and keep us posted

 

[Conceyted]

I had also read about types of sand leeching phosphates, but the sand I chose (Reefflakes) seemed to be touted as having zero phosphates. My thought are that during my nutrient problem times the sand absorbed some bad nutrients that it is now contaminated with. Doing some sand vacuuming followed by some large water changes sounds like a good idea. I might give that a go!

 

[Allmost]

Well, if I continue vinegar dosing I don't need to siphon the sand ever because the hair never grows. Or do you mean I should begin to remove the sand but still continuing to dose vinegar while I do so?

as you stated, the sand has became dirty.

you can either remove it, replace it, or live with it. the way to live with it is to siphon it weekly, to "clean it up" a bit, and lower nutrients sank into it.

I personally like carbon dosing, as it locks up nutrients in biomass of bacteria, which in turn becomes food. so I advice it.

Id continue dosing vinegar, to have control on the nutrients. Siphon the sand, to remove the "detritus" and bacteria build up, and feed the corals, to allow them to gain their colors.

thats just my opinion though there are alot of ways you can go about this and my method might not be the best.

 

[Conceyted]

as you stated, the sand has became dirty.

you can either remove it, replace it, or live with it. the way to live with it is to siphon it weekly, to "clean it up" a bit, and lower nutrients sank into it.

I personally like carbon dosing, as it locks up nutrients in biomass of bacteria, which in turn becomes food. so I advice it.

Id continue dosing vinegar, to have control on the nutrients. Siphon the sand, to remove the "detritus" and bacteria build up, and feed the corals, to allow them to gain their colors.

thats just my opinion though there are alot of ways you can go about this and my method might not be the best.

Thanks for clarifying. I guess what I am afraid of is that the carbon dosing is what is causing my corals to be pale. I was trying to find a way to stop carbon dosing for a while, as that appears to bring color back to my corals.

 

[Allmost]

Thanks for clarifying. I guess what I am afraid of is that the carbon dosing is what is causing my corals to be pale. I was trying to find a way to stop carbon dosing for a while, as that appears to bring color back to my corals.

carbon dosing is in fact making your corals pale. its lowering the N and Ps. this is not always bad, as it will give you more power in brightening corals ... via feeding. but I understand thats not for everyone.

now if you stop, and remove the sand and go bare bottom. What will take care of the nutrients, so 1 year from now u wont have the same ISsue ? nutrients could bond to your rocks. you could run GFO and use other methods of course. but make sure to have a long term plan

Im just typing these so u can consider it long term and all different things that can happen.

 

[oscarinw]

Carbon dosing seems to be associated with some form of 'burnt tips' in this article but not really discoloration. If anything, the opposite.
http://reefkeeping.com/issues/2008-08/nftt/index.php

I would support the cleaning of the sand via syphoning, stirring and water changes.

 

[Allmost]

Carbon dosing seems to be associated with some form of 'burnt tips' in this article but not really discoloration. If anything, the opposite.
http://reefkeeping.com/issues/2008-08/nftt/index.php

I would support the cleaning of the sand via syphoning, stirring and water changes.

"burned tips" can happen in Ultra low nutrients systems, where KH [alkalinity is high]

skeleton grows faster than the coral can make tissue.

the lowering of N and P in water around the coral, will stop fueling overgrowth of Zoox algae within corals, which gives then the brownight darker look, the less Zoox, the more pale a coral is.

now a coral with Limited Zoox and N and P around it, will consume foods to get its energy, which in turn can feed the color pigments to make corals colourful


another good article Here

 

[Conceyted]

I forgot I'm also still running carbon and gfo along side the vinegar dosing.

When I get home I will begin reading all of your articles, Allmost. Thanks very much.