Need some advice after accident resulting in large GHA outbreak

[offtropic]

So I am looking for advice on how to handle a large GHA outbreak in an otherwise high water quality tank. Tank size is 90g with 1 rabbitfish, 3 wrasses, 2 clowns, 1 blenny and a few trochus and nesarrius snails. Use filter floss, algae reactor and skimmer for nutrient removal.

The tank didn't have any algae issues until I had an accident before a business trip about a month ago where I was setting up an autofeeder and ended up spilling/dumping about 2-3 weeks worth of food into the tank where it was instantly dispersed by my powerheads. I did my best to get out all I could but had to leave later that evening. My immediate goal of getting enough out to save the livestock from a mass ammonia spike seemed to work as everything was still alive when I returned.

However, within a few days of return GHA started to grow almost out of control and I've been working ever since to control it using water changes, manual removal (about 20-30 minutes/day) and cutting back on my feedings (I used to feed pretty liberally). This manages to keep it barely in check and keep my corals free from getting their light blocked. Unfortunately, the stuff just keeps coming back. Water quality conditions are really good with 0 ammonia, 0 nitrite, 0 nitrate, 20ppb phosphate (yes I realize the algae is sucking some of these in as fast as it is being created), 83dkh and calcium/magnesium within ranges you find on SPS tanks.

So, what is the best approach here? Water changes will obviously have no effect as nutrients actually in the water are at 0 (I do AWC of 20%/week as is). Do I need to just keep at it with manual removal? More herbivorous livestock (suggestions here?)? Do I cut lights for a couple days (in which case do I need to worry about my corals?). Help!

 

[kchristensen8064]

I had the same issue and actually was getting false readings on my nitrate and phosphate tests, due to the algae consuming it fast enough that I couldn't get an accurate reading. I started running Rowaphos in a reactor and in just about 4 weeks I'm getting close to being algae free. I replace the rowaphos every other week to keep its phosphate absorption working. This has been a life saver for me. I was on the verge of breaking it down and starting over. I could reach in and pull out solid chunks the size of a baseball daily.

 

[Mical]

Up your mag to about 1500 that'll slowly kill your GHA. I had similar a couple of years ago used Kent Tech M as per directions, gone in two weeks. Guy who told me of this was fish store in Colorado - Neptunes -

 

[Kalibur2]

I had a lot of GHA. What helped me was the Manual removal and I also used phosphate e from brightwell. I used a 5 micron sock to add the phosphate e. I used below recommend amount as I was worried about lowering phosphate to quickly and killing my sps

 

[jeffchapok]

Get your nutrients under control to hinder further growth.

Lower white lighting.

Scrub and vacuum as much as you can.

A pincushion urchin will clear a lot of GHA. Emerald crabs will eat some too. Astrea, nerite and turbo snail will help as well.

 

[offtropic]

I had the same issue and actually was getting false readings on my nitrate and phosphate tests, due to the algae consuming it fast enough that I couldn't get an accurate reading. I started running Rowaphos in a reactor and in just about 4 weeks I'm getting close to being algae free. I replace the rowaphos every other week to keep its phosphate absorption working. This has been a life saver for me. I was on the verge of breaking it down and starting over. I could reach in and pull out solid chunks the size of a baseball daily.

I think the readings are accurate (there is no nitrate or phosphate in the water) but that it is just being taken up as fast as it is produced. I'll look up what rowaphos is and how it works but you didn't have any problem with any of your corals when you introduced it? I'm worried that something that can out-compete the algae for phosphate will also easily out-compete the corals.

 

[offtropic]

Up your mag to about 1500 that'll slowly kill your GHA. I had similar a couple of years ago used Kent Tech M as per directions, gone in two weeks. Guy who told me of this was fish store in Colorado - Neptunes -

Did you have any other issues when you upped your mag (think I'm currently around 1360)? Did you take any other measures at the same time?

 

[offtropic]

Get your nutrients under control to hinder further growth.

Lower white lighting.

Scrub and vacuum as much as you can.

A pincushion urchin will clear a lot of GHA. Emerald crabs will eat some too. Astrea, nerite and turbo snail will help as well.

Yeah I've been working on getting those nutrients down but there was just so much injected into the tank in one huge blast that I think I hit some sort of tipping point where the algae sustains itself. I currently have almost no whites on the AB+ schedule but should I just go dark for a few days? How does SPS handle that?

I haven't used urchins before...are they reef safe and will my haliochoeris wrasse leave it alone?

 

[kchristensen8064]

I think the readings are accurate (there is no nitrate or phosphate in the water) but that it is just being taken up as fast as it is produced. I'll look up what rowaphos is and how it works but you didn't have any problem with any of your corals when you introduced it? I'm worried that something that can out-compete the algae for phosphate will also easily out-compete the corals.

My corals have never looked better! They are looking amazing now that they aren't having to fight the algae for space and light!

 

[Phil D.]

What is funny is that the Kent Tech M is the only Magnesium additive that will kill off the GHA at the higher levels. There won't be any issues with Mag at 1500. I was told this tip many years ago by my LFS and that the Tech M is the only one to work.

 

[offtropic]

What is funny is that the Kent Tech M is the only Magnesium additive that will kill off the GHA at the higher levels. There won't be any issues with Mag at 1500. I was told this tip many years ago by my LFS and that the Tech M is the only one to work.

Did you keep mag at 1500 after or did you lower it again? My fresh salt (cycled in through my nightly AWC) is about 1390 so not too far off .

 

[Phil D.]

Left Mag alone, and it SLOWLY went down from WC. Thins were fine throughout

 

[offtropic]

Ok decided to add a sea hare as I prefer biological over chemical control where possible...if it doesn't work I'll try some of these great solutions posted. Thanks all. I'll keep you updated.

 

[kchristensen8064]

I hope you get a good one. I tried 2 and neither one would eat anything.

 

[KorD]

I have a short spine urchin.. I love that guy.. pencil urchins are also amazing. Both are reef safe and the ones I will always have.. tuxedo urchins I would stay away from, they like to wear zoa's shells and other things as outfits. Unless you like a roaming zoa garden [emoji23]