Help!! Cyano problem

Hey guys. I have been battling a cyano problem for months. I have tried everything. 3 day blackout. Reduced lights. Changed light settings. Added flow. Cut back on feedings. My phosphate and nitrate levels read near 0. Not sure what else to try... I also have it growing in my refugium. I am using a GFO/ carbon reactor to help keep phosphates under control.

I haven't tried chemicals yet as most people suggest against it.

Getting desperate. It is frustrating me to the point where the hobby isn't fun as I have to scrape and cyphon my tank daily now. Can anybody in the metro area assist? Possibly take a look and tell me what I am doing wrong?

 

The tank is 6 months old. It is a 65 gallon tank with a 29 gallon sump. I do a17 gallon water change every 2 weeks.

I should permanently remove the sand? And replace it with what? What phosphate removers would you recommend and what are the potential negative side effects?

 

Thanks guys for all the info!!!

Just as a follow up...

I did just check my phosphate levels. According to my Hannah Checker, I am at 0ppm for phosphates. My nitrates are at 5ppm. Salinity is at 32.6ppt and pH is at 8.1 (although we have had pretty big pH swings - it varies anywhere from 7.7 to 8.1). I am using a custom Kalkwasser Reactor that I built to dose with Kalk to try to keep my pH up. I doubt that really impacts cyano growth though?

I do already have a diamond gobi in there. He seems to do a pretty good job. And I have quite a few sand sifting snails (I can't remember what they are called - sorry). I do not having any fighting conchs yet, but will definitely pick a few up (if anybody is placing an order from Live Aquaria, let me know!)

I have two power heads in my tank running right now for flow. I ordered a third to increase it a little more. I also have a MJ1200 powering a custom UGJ system I built. It doesn't add much flow, but a little....

We do target feed our coral. Do people usually do that? We are using Rod's Original Reef Food plus mixing with Coral Frenzy. What are people's thoughts on this? Perhaps that is having a negative impact? We do that every 2 to 3 days.

The temperature in my tank hovers between 80 and 81 degrees. Is that a little high? I don't have a chiller in my system - and my heater is set at 77, but it seems as though the water is always a little bit warmer than that. I was hoping to avoid buying a chiller, but perhaps my temps are a little too high?

 

Here is a picture from just a few minutes ago. It is getting worse! Grr!!!

 

My TDS is 0. I don't have a RODI yet so am buying jugs of RODI drinking water from HyVee. At least I assume their water is 0 TDS!

So if the algae consumption is causing zero reading, how do I know if phosphates are my problem? What else can I do to help with that beyond what I am doing already?

Will blowing a fan in my sump cause a realistic temp drop? Does that really work? Seems like blowing a fan at the surface wouldn't do much to chill it. But maybe I am wrong? I agree the temp is a little high. Just didn't want to drop another $300 on a chiller...Unless somebody has a cheap one they want to sell me!

 

Has anybody tried chemiclean? Everything I have read seems to be good and it says that it works well. But people on here say to stay away from chemicals. Wondering why?