Brown polyps - nutrient issue - or something else?

[gex23]

I've really struggled to get my SPS to gain colours - the polyps, in particular, go a light to dark shade of brown and stay that way.

Now from what i've been reading there's a lot of contradiction as to the cause of this - some say excessive nutrients are causing excess zooxanthellae algae to grow within the coral, yet others say it's caused by a low nutrient load.

Now a bit about my tank. It's a 130 litre 60 x 45 x 45cm tank which has been setup since January this year - initially I lit it with an original AI Hydra and all was well and good - I got great colours and good growth. This tailed off a bit and I swapped to 2 x Kessil A360WE around 12 weeks ago now - I was never happy with these lights and found the colour rendition poor in all aspects - my Forest Fire monti lots most its growth tips and green fluorescence, among with numerous other casualties. After putting a PAR meter on the tank it was showing very low PAR figures top to bottom and thus put it down to poor light and upgraded to an ATI Hybrid (8 x 24w T5 + 75w LED) last week which gives much better rendition and also much better PAR figures.

Also I was initially using RSCP salt for my weekly 10% WC but found that the ALK swings were unacceptable - I have now thus swapped to Tropic Marin Pro Reef salt to maintain levels more in line with NSW so unsure if the swings are also what caused these brown colours?

System spec :

130L 60 x 45 x 45cm
18kg Live Rock
Sand Bed 4cm average
ATI Hybrid 8 x 24w T5 + 75w LED
Vortech MP10 x 2
X-Aqua overflow / Return
Eheim compact 5000+ return pump
AFM Marine skimmer (450L rated)
100 micron filter socks
5 litres Siporax media
HOG1 Algae scrubber
Bio Phos 80 phospate media in reactor
Dosing Alk and Cal via Kamoer doser with Fauna Marin trace additives following the balling lite method
Auto top up for fresh RO

Inhabitants (fed with a pinch of pellets twice a day, 1 cube of frozen once a week and gold pods twice a week)

2 x Percula Clownfish
1 x Royal Gramma
1 x Hectors Goby
1 x Peacock Wrasse

5 x red legged herbits
Various turbo, bumblebee and Narcissus snails

I perform 1 x 10% water change each weak with TMPR salt @ 1.026 SG

Parameters are as follows

Temp - 26 C
SG - 1.026
KH - 7.3
Cal - 450
Mag - 1400
PH - 8.0
Nitrate - 0.5
Phospate - 0

Just to add - the polyps of my SPS show great extension - just poor colour?

Sorry for the excessive detail but I thought it may help narrow down why my tank looks so crap.

Regards

Anthony

 

[Reef Frog]

I'm no expert, but the colors in your birds nest look OK to me. Can't really tell on the coral in the foreground as its a little blurry, but it didn't look brown to me.

Your T5 fixture looks like it's mound fairly high. Not sure but am wondering if a little more intensity (by lowering it) could be beneficial? Just a thought. But if everything is good, I wouldn't mess with it. Your parameters & methods look fine. Nice tank.

 

[gex23]

I'm no expert, but the colors in your birds nest look OK to me. Can't really tell on the coral in the foreground as its a little blurry, but it didn't look brown to me.

Your T5 fixture looks like it's mound fairly high. Not sure but am wondering if a little more intensity (by lowering it) could be beneficial? Just a thought. But if everything is good, I wouldn't mess with it. Your parameters & methods look fine. Nice tank.

Do you not think it looks dark for a pink birds nest coral?

I'll get some better photos of the coral in the foreground later.

The reason the ATI Hybrid unit is mounted so high is to not shock the corals - the intensity and height will be adjusted over the coming months.

The hysterix was never brown before the Kessils - but then as I say it could be nutrient levels, flow or parameter swings I guess?

 

[Dugless]

How are you measuring your phosphate?

 

[powder_blue]

Nutrients

 

[gex23]

How are you measuring your phosphate?

Salifert phosphate kit.

Nutrients

High or low?

 

[reefmutt]

Smart to start with the t5 up so high..
Do you ever use carbon?
My first guess would be low nutrients.. If that p reading is accurate.
My suggestion would be to stop using the gfo.. Or use less of it..
Or maybe try an amino acid, or feed a bit more..
And give those lights a bit of time to do their magic..

 

[Icefire]

Well you said kessil browned your coral in the last 12 weeks and you just barely switched to T5 one week ago? could take weeks-months to gain them back.

I would wait 2 months before changing your routine

 

[DaveRaz]

I agree with icefire. I changed my lights from maxspect razors to this set up and it took about 2 months for the corals to gain color and start growing again. VERY slow growth with the razors but now I notice much better growth and color from week to week. In sure the razors grow coral but I didmt have the patience to keep tinkering with the photoperiod and settings. I run three kessils pretty high intensity and the T5s are running 7 to 9 hours a day at 100%. I don't dim them. In two months or so you will see a good improvement.