likely cause of my cyano

ive been dealing with some cyano on my sandbed. i red a bit about it and decided to put another koralia into my tank. no matter which way i adjust it my sand is blowing and getting on my rocks so i want to take it out. before i put this extra koralia in the tank (55 gallon) i have 2x 800 gph powerheads and one 400gph....also my return which is about 300 gph. my flow was pretty good without it. i think what may have lead to this cyano is me starting to feed frozen mysis shrimp. the way i would feed is cut one of the cubes in half and just put the frozen food in my fingers and dip it into my tank....it would melt and the fish would eat it. i noticed after doing this the water actually would smell like the shrimp for a half hour or so. did feeding this way and putting all that nasty juice in the water cause this issue? im not doing it a anymore. i feed every 3 days and have a coralife 65 skimmer and skim wet.

 

Depending on the brand of shrimp, it can have phosphate binders, which would be leading to your cyano outbreak.

I would take the shrimp, defrost it outside the tank, and strain off the liquid that comes with it. Then, you get rid of that extra gunk.

 

Your feeding was adding phosphates to your system. Thaw the frozen in water, pour the thawed mix into a brine shrimp net and put the food in your tank.

You will need to get some granulated ferric oxide to remove the phosphate from your system. Also check your alkalinity and get it to 10dKH this will help some also. Make sure you are using ro/di water to make up your saltwater.

 

Algae problems are usually caused by aquarium water with excess nutrients like phosphate, nitrates etc. You can try and siphon out what you can to remove the algae in the short term. In the long term you may have to examine how you care for your tank. There are some commercial dry foods also contain excess nutrients and other undesirable things like nitrates, phosphates etc so I strain/rinse my fresh/frozen foods before feeding my tank. You may want to consider feeding your fish less often. Also using RO/DI water and a high quality salt with little if any NO3, phosphates etc like Tropic Marin will really help too. Adding a phosphate remover and increasing flow in your tank may help too.

 

How old is your tank? If it's a fairly new tank, this is expected and will go away. If it's an established tank, then try the suggestions already mentioned.

I recently switched my brand of frozen mysis because the LFS did not have the one I usually buy....within a few weeks I started seeing little signs of algae problems, the brand does make a difference.

sounds like you have good flow.
Make sure you're using RODI water
Try rinsing the frozen food
Depending of number of fish, try feeding less (maybe cut-back a few days)
Do a few water changes
Try running some gfo (like puro phoslock) in a bag or reactor for a few days. I have a phosban reactor but from experience the bag works just as good so I rarely every use the reactor.