Why don't my corals grow?

TonyB · Jul 7, 2009

So the majority of the corals in my system grow at a rate which I would consider to be slow. Most SPS take a month or two to encrust a plug then seem to stall and not grow much after that. I have some euphyllia sp. that were purchased as two heads and now have five after two years. I have an orange digitata that in three years has grown from a frag to a colony that is roughly 6x6". I have seen this same coral take over other club members' tanks.

Tank is a 120g, 4x2x2'.

Lighting is 2x250w radium 20k on M80 ballasts. Photoperiod is 8am to noon, then 6pm to 10pm. I used to run XM 10k's and had the same problems then too.

Flow is two Vortechs running about 80%.

Water changes are 20% bi-weekly with IO salt.

Water parameters;
SG 1.025
NO3 .05 (according to awt.com. NO3 does not register on any of my kits)
PO4 .01 (Hannah and awt.com)
Ca 400-420
Mg 1250-1300
Alk 10-12 dKH
ORP ~380

So I've got two theories. Either the split photoperiod is the cause, or a club member mentioned that the low nutrients may be to blame. Can any of you think of something else that may be to blame? The photoperiod I can fix easily but how would I go about supplementing the system if we feel that the low nutrients are to blame? I was blindly dosing Brightwells aminos for several months but didn't seem to notice a difference.

Thanks for reading!

COReefer · Jul 7, 2009

I'm really not liking the idea of the split photoperiod. why do you do this??

tc269 · Jul 7, 2009

I would blame the split photo. I never liked that kind of setup. What are the colors of your corals? Dark, Pale? You might want to try reefcrystals from IO also just to through some more ideas out there.

ahayes13 · Jul 7, 2009

well i would say its a shot in the dark on the actual cause. every persons tank seems diff. and there growth rates different. but it does sound like yours are growing slowing than any type of normal. i would suppose its a hit or miss type thing and will take some time to diagnose. the split photo period seems a little odd to me and all your parameters look good. i think the first thing i would do is to change your ligthing schedule. and see what happens from there....

lvsuckerfish · Jul 7, 2009

IMO you are asking a loaded question it could be a couple things and it could be just the kinda coral and how they are aclimating to your tank. I have frags in my tank that still haven't started to encrust. I also have others that are encrusted over and started on the rock already. Nothing fast happens in reefing but diaster. being that said what kinda corals and are the corals happy were they are at. the split photo period I personally do not like the Idea but again it is my opion. It could mean time and patience as for the parms look good. my tanks is way off from the normal for me to get good growth. I like everything High from cal to mag to alk all high. but it works for me and how I do it I have no clue when my ca and alk are @ 420 8 I loose corals and growth when high everything is happy. also try and move things around look at the pylop extension and move from there they may not be happy.

amore169 · Jul 7, 2009

I am in no way an expert but IMHO about ur temperature is it stable, do u run a refugium, have u tested for stray voltage.

Sikryd · Jul 7, 2009

Tony - from everything I have read - if you are running low nutrients, the alkalinity should be kept around 7dkh - running above that will stunt growth and cause "burning".
I don't know from experience since I run mine at 7. I know when it went up to 9 things got allllllll out of whack, my grandi's got "burned" and all kinds of other stuff. Good times......now I watch it more closely. I guess it is a parameter that needs to be kept fairly constant when running a low nutrient system.
My tank isn't mature enough to speak from experience on this - so maybe someone else that runs a low nutrient system can chime in.

As for the light thing - that is a no brainer for me. The coral has no time to "ramp up" and ramp down, as far as eating/sleeping. I know my corals are stimulated by the light to eat, just by watching the tank when the lights change from dusk to night.
They also require a 12hr rest period to grow. But if they aren't getting that but every 2nd cycle of lights - I would imagine that would mean they would grow 1/2 as much.
Just a theory though.....

Reef Pets · Jul 7, 2009

I would have to say the issue is the photoperiod. dkh is a little high but if the tips are not burnt then it should not be an issue. I use to keep my dkh between 12-14 and I never had a growth issue.
Change your photoperiod to at least 10 hours per day, with them being on constantly on 10 - 11 hours and you should see a huge difference. Even with the hours that you are running them you are only getting 8 hours a day. I have never heard of having the photoperiod split..

If you work first shift then turn your lights on before you get home, say 3:00pm and have them turn off 1:00 - 2:00am. This way you can enjoy your reef while you are home and the lights are on during the cooler hours of the day.

crabbejoe · Jul 8, 2009

Do you have any softies in your tank? They can slow the growth of hard corals.

jendub · Jul 8, 2009

Are you feeding? If so, what?

tc269 · Jul 8, 2009

oh also this will help tell what kind of nutient level you are at. how often do you have to clean your glass. every day? every other? every 4? once a week? or how do I clean my glass? I know not the most precise way but a good indicator.

Nate82 · Jul 8, 2009

That photo period is throwing everything off..

chappy · Jul 8, 2009

seems to me if you run your dkh that high you would benifit from higher mag and a little higher ca your big 3 seem a little at odds with each other

TonyB · Jul 8, 2009

Thanks for the replies.

Something I forgot to mention is that I've also got a bunch of macro algae in the sump that doesn't grow either which is part of what led me to believe the system may be starving. I have cheato and a type of caulerpa. They are lit by a power compact bulb that is on from 8pm to 8 am.

I'm going to reprogram the aquacontroller to straighten out the photo period. I had done it because of an article I read a while back about corals only utilizing light for 3 hours or so. Guess that theory is blown out of the water :) We'll give that a go and see what happens.

it could be just the kinda coral and how they are aclimating to your tank.

I would agree with this but many of these corals have been in the system for years.

Are you feeding? If so, what?

Nothing to the corals directly. The fish are fed Omega One flake a couple times a day and I have my own frozen food with brine shrimp, mysis, clams shrimp and krill.

oh also this will help tell what kind of nutient level you are at. how often do you have to clean your glass. every day? every other? every 4? once a week? or how do I clean my glass? I know not the most precise way but a good indicator.

Not sure what you mean. I listed all the parameters in the OP. I have to clean the glass every 4-5 days or so.

Sikryd · Jul 8, 2009

I would also try feeding artemia, oyster eggs, rotifers, and cyclopeeze. I put it in with my fish food concoction and put a spoonful in 3x a day. I'm sure a lot is wasted, but the fish are fat and happy, the corals seem to be pretty thrilled - and that makes me happy :feel_good: That is what I do since my nit's and phos is so low. I can't grow chaeto to save my life either. Which is fine with me,.

starfish · Jul 8, 2009

Is it not true you get your best growth rate because of the higher par rating with 10k lamps, 14k's a little less par but better blue color and 2ok's have the lowest par rating corals grow much slower with these bulbs but you do have great color.....so to me it boils down to what you want out of your tank......decent growth rate and color with 14's or great color and slower growth rate with 20 's. Matter of individual preferance.

tc269 · Jul 8, 2009

ok if you only have to clean the glass every 4 days your at a low nutrient level... just cause a hanna tells you 0 PO4 does not always make it true. it can often times be bound up in algea and the algea feeds off of it so that your levels say 0 cause the algea has it all. make sense?

TonyB · Jul 8, 2009

Yes, I understand that. There is no algae to be found in the system. A slight film on the glass every 4 days.

I reprogrammed the ACJR today and the lights are on from 1:30-10:30 we'll see how it goes.

I'm going to let it go for a few months with that being the only major change. In the meantime I want to start researching what to supplement in case the low nutrients are to blame. What is the recommended product and procedure here?