GFO, Phosphate, Cyano

[Bill Nye]

My GFO reactor broke 5+ days ago and I just received the replacement in the mail. I checked my phosphate levels using a Hanna Phosphorus checker and the reading came to 6 which when you do the conversion is .006.

My tank is 8 months old and I have battling cyano. My phosphate readings are always low and my nitrate has always read 0 on a salifert nitrate test kit. The cyano has been getting better slowly despite my reactor being off. My sps which have been doing well seem a little bit darker color but maybe thats my imagination.

My question is should I use the new GFO reactor even though my phosphates are low? If my nutrients are low why do I have cyano?

 

[SoloGarth]

GFO is one of those things that should be used sparingly. It can have negative effects if too much is used.

If you are planning to continue using GFO I would start the Rx back up with 1/8 the amount you used previously. You can watch the tank and monitor phosphate and adjust later on if necessary.

 

[CStrickland]

Cyano seems adept at finding areas of high phosphate. I think that's why it grows in low-flow zones. So while your tank water generally might be .006, you may have higher levels right under the cyano because, for example, detritus is accumulating there and decaying. After a while that little spot can get saturated, and by growing right on the rock or sand in question the cyano catches the phos as it is released from both the detritus and the rock itself before it can be carried to the gfo for removal. So while the reactor is working to lower phos in all the water that passes through it, it can be out competed by the cyano until those underlying issues are addressed or over time the tank evens out to low overall levels.

 

[Mark426]

The Phosphorus to Phosphate conversion is 6 x 3.066/1000 = 0.0183 , but you probably already know that. IMO...your PO4 or Phosphorus if you prefer, is just about right. Almost everyone agrees that some PO4 and Nitrate is needed for healthy SPS. That doesn't answer your question about cyano however. SoloGarth has the best answer so far.

EDIT: Handy Chart
http://www.pny.se/aquarium/

 

[Bill Nye]

The Phosphorus to Phosphate conversion is 6 x 3.066/1000 = 0.0183 , but you probably already know that. IMO...your PO4 or Phosphorus if you prefer, is just about right. Almost everyone agrees that some PO4 and Nitrate is needed for healthy SPS. That doesn't answer your question about cyano however. SoloGarth has the best answer so far.

EDIT: Handy Chart
http://www.pny.se/aquarium/

Thanks Mark! Brain fart. I was typing late last night after a few Guinness.

It has been extremely frustrating dealing with Cyano considering my nutrients are low/optimal and I do full maintenance every week during my water change and I still am having problems. I have 0 other types of algae growing on my rock and I only need to clean my glass about ~1-2 times per week. The common advice of lower nutrients doesn't seem to apply to my situation.

I am going to leave the reactor offline and continue to monitor phosphate. If it gets up to >.03 I will go back to GFO.

 

[Buzz1329]

The Phosphorus to Phosphate conversion is 6 x 3.066/1000 = 0.0183 , but you probably already know that. IMO...your PO4 or Phosphorus if you prefer, is just about right. Almost everyone agrees that some PO4 and Nitrate is needed for healthy SPS. That doesn't answer your question about cyano however. SoloGarth has the best answer so far.

EDIT: Handy Chart
http://www.pny.se/aquarium/

Thanks for the charts. Just what I was looking for!

Me

 

[Reef noob_]

When i had an extremely bad cyano outbreak in my last tank i put on GFO and it actually got worse, then right after taking it off the cyano died away, i think the best way to combat it is to reduce the nutrients going in and get more out by skimming and water changes.

 

[reefgeezer]

Many photosynthetic bacteria, including IMO Cyano, use the nutrients bound in dissolved organics. Those nutrients don't show up on test kits, You have to export or bind those organics to starve the bacteria. Among other things, wet skimming and a lot of GAC can do the trick. You might also investigate the area where the Cyano starts. As CStrickland said, there may be some local organic source like a decaying snail or something there. Sometimes increasing the flow in that area disperses the organics before the bacteria can use them.