Help: SPS bleaching and STN

Hi everyone

I am looking to get some help with my tank. I'm experiencing some STN and coral bleaching on my SPS. All other corals look great.

Tank Volume: 70 gallons
Lights: 6 x T5HO (1 bulb changed per month)
Photoperiod: Currently at 5 hours for all 6 bulbs
Water movement: 4 x MP10 (80%), Hydor 1400 behind rocks, Eheim 1262 return
Protein Skimmer: Bubble Magus NAC5e (rated at 80 GAL - 120 GAL)
Barebottom reef techniques
Tank was started mid December 2012. All corals and rock transferred from my other barebottom tank that was started in June 2012.

Maintenance schedule
- clean filter sock after blasting rocks with turkey baster (daily)
- clean protein skimmer cup (full cup daily wet skim)
- wipe tank walls down (daily)
- 5 gallon water change with treated tap water (weekly), siphon out detritus that collects at the bottom
- test parameters (check ato, dosing mix) weekly

Parameters
- Salinity 1.026 (refractometer)
- Nitrate 0 (API)
- Phosphate 0.02ppm (Hanna ULR)
- Calcium 450 (Salifert)
- Alkalinity 8 (Hanna)
- Magnesium ??
- PH ??
- Temperature 25 celsius

Stock list
- 2 clownfish
- 1 blue hippo tang
- 1 tailspot blenny
- 1 lawnmower blenny
- 1 scooter blenny
- 2 green chromis
- 2 yellow chromis
- 3 peppermint shrimp
- 2 mexican turbo snails

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I was dealing with cyano and contributed this to the fact that my lights were on for 8 hours each day. Plus I was overfeeding the tank (did not defrost frozen before feeding fish). To combat it, I have been blowing my rocks off on a regular basis, and dosing one drop of Zeobac per day. It is working. There is a problem with red hair algae though.

This green stag colony started bleaching from the middle of the colony out. At first I thought it was AEFW but it wasn't little circles that disappeared (never verified or checked). Now as you can see, entire branches are bleached. What is strange is that the polyps are still there and at night, I get full polyp extension.


This acropora colony (sorry don't know what type it is) started dying out at the tips. You can see the algae growing on various tips. My ALK levels were consistent. I'm slowing trying to bring the levels up higher to 8.5 - 9 DKH range though.




Any help would be appreciated. I do have plans to switch to an RO system, but that won't be for another couple months. I do feed my corals with reef roids 2 times a week.

Here is a full tank shot.

[waynemah]

Do you use anything for controlling phosphate / nitrates? You mentioned that your using Zeobak... Is it the whole system? I've had similar results when my zeovit reactor had too high of a flow rate. Also, when trying biopellets.

[cuz]

with the amount of rainfall lately and you using tap water I'd be curious if the water quality has changed on you?? how long ago did things start changing?

Hi Wayne

I was dosing vodka at 1ML per day, but stopped it completely when cyano appeared. That was my only form of nutrient control. Only dosing Zeobac (bacteria) to help with the battle against cyano. There is a bag of carbon hanging in the sump (passively).

Now I am just rely on wet skimming for nutrient control.

Larry, I think your onto something. It started right when spring hit. So about a month now?

[Myka]

I would suggest you go to a water store and buy 40 gallons of RO water and do a couple 20-gallon water changes in the next week. Also, with STN I find a lower alkalinity level is often better. Your calcium and alkalinity aren't balanced btw either.

If you have too rigorous algae growth in your tank it will starve your corals of nutrients causing bleaching. Algae also release toxins of sorts that inhibit coral growth and can really harm corals if it is out of control. I've experienced this myself.

Another thought is that I don't think those MP10s are really strong enough on that size tank for SPS. I think it would have been better to buy two MP40s. If you have any more powerheads on hand you could try adding more flow.

For feeding, feed the corals in the evening jut before lights out and turn the pumps off for an hour so they can feed. Then by morning the food will be filtered out by your skimmer and filter sock. Filter socks tend to really help with cyano if you change them out every 2 days.

Thanks for the tip Mindy. I'll give those suggestions a try.

[asylumdown]

how are you maintaining alkalinity? Are you using an auto-doser? I had problems like this on my old tank when my alk levels weren't stable over the long term.

I am using a bubble magus dosing pump, dosing two part. Using baking soda (arm and hammer).

[gregzz4]

Originally Posted by Myka

Another thought is that I don't think those MP10s are really strong enough on that size tank for SPS. I think it would have been better to buy two MP40s

You think 4 x MP10s isn't enough for a 70G tank ?

I'm running 2 x 10s in my 75G and can't run them @ 100% without either blowing flesh off corals/polyps stop growing on one side, or causing them to grow sideways away from the props