Removed cyano now onto the Gelidium (red turf algae)

[charterreefer]

I have just gotten rid of a small amount of cyano (with several treatments of chemiclean) only to see gelidium starting to spread throughout the tank. Yeah, it sounds like everything I've read...you get rid of cyano then some other opportunistic algae steps in to compete for the liberated Po4 now in the water!
A little history on my setup: Its a 2 year old 300 gallon (total) system (250 gallon DT) that has had 10% weekly water changes since setting it up (yes, every week). 1 cup GAC changed about every 4 weeks. I don't feed excessively (2x a day) and only have 12 smaller sized fish. Coral get 2 teaspoons oyster fest 2 x a week and Phols extra is dosed with 1/2 of recommended amount.The tank is all sps (healthy, good color). No gravel bed and lots of live rock in 75 gal sump that is suspended off the bottom with eggcrate, 5- mp40 powerheads making sure there are no dead spots in DT, oversized reef octopus skimmer, Calcium reactor and a 40 gal refugium. Water parameters: Ca ~460, dKH ~8.3, pH 8.0-8.2. NO carbon dosing or biopellets used. I always thought I had a ULN system; reading 0 nitrates and 0 phosphates. I never used GFO thinking that the water changes were taking care of NO3 and PO4 levels...I guess not! PO4 was most likely tied up in the cyano.
The final Chemiclean treatment is finished today. I will be doing a 80 gallon water change in hopes of giving the system somewhat of a reboot and will be starting to use 1 cup of gfo (because I'm just starting to use it in tank and don't want to shock the delicate sps). I started to dose nitrate as well (in the form of calcium nitrate) to bring up the level from 0 to 1 ppm in hopes of tipping the scale toward seeing a Slight amount of green growth as opposed to the cyano. It will help in dialing in the redfield ratio to help deal with the PO4 issue too.

Will Gelidium (red turf algae) start to be reduced by getting the PO4 level close to zero? I have read horror stories on how to get rid of this stuff but am hoping it was from people with high levels of nutrients in their systems. I'm almost sure that I used to see very small amounts of this stuff (with my mesoscope/ high magnification) on the rocks for years! I'm hoping it will go back to a more dormant state once the phosphate level is in check. Maybe I'm mistaken.
Any thoughts or advice would be greatly appreciated.

 

[horseplay]

If you have not used gfo before it might strip you water too clean. So be careful with that. I would not use gfo as a long term solution. Carbon dosing is easier to implement and more flexible.

As for whether the algae will go away, it's hard to say. When your tank is balanced algae should be in check at least. I would add some clean up crew if you do not have already. Emerald crabs are especially good at removing turf algae. My tank always have phosphate and nitrate now but I do not have an algae problem. So You cannot depend on reducing nutrient alone to control algae.

 

[charterreefer]

Thank you for the reply. I am starting slow with the GFO. Thanks for the warning. From what I know about carbon dosing there needs to be a measureable amount of NO3 present to start, otherwise you will get an algae bloom from the unused carbon that is being put in the water. Why do you have detectable nitrates and phosphates if you are carbon dosing?

Yes, I do have a cleanup crew. Although, since starting the tank I haven't had any algae to deal with except the cyano that crept in 4 months ago.
I have always read conflicting reports on emerald crabs. Some say to use only females. Some seem to think that Mexican turbos are the ticket for the red turf algae. They seem to be the only snails that stay on the rocks instead of going on the glass like my trochus snails do.

Anybody else want to weigh in on this?