Brown/Rust color algae on substrate

1st. DO A BIG *** WATER CHANGE. But do it over a two week period stagering it about three days apart. I would change out around half the water volume, as I am SURE chemicals got in your tank from the steam cleaning. They always do unless you cover your tank VERY VERY well, until they are done.
2nd STOP WASHING YOUR HANDS WITH SOAP BEFORE PLACING THEM IN THE TANK!!! LOL!!!

3rd DO more frequent water changes, and take the micron sock off of the intake. You only need it if you house SMALL fishes or dwarf seahorses.
It realy sounds like you are starving your tank of proper nutrients through
in-frequent water changes. Vital elements are replentished with each water change.

DO you house anything other than the two fish that died at this time?

DO you dose anything into the tank?

Also I am not a big fan of chemipure or purogen.
THey make your tank reliant on the chemicals and less likely to grow the proper amount of organisms needed to self sustain.

If your tank was set up as a fish only tank with live rock you REALY should have had another type of filtration running in combination with the skimmer.
You should have at least had an H.O.B (hang on back filter).
Most fish are heavy eaters and salt water fish defecate MUCH more than a fresh water species because thier metabolism is higher due to the salt.
If you don not provid proper filtration for thier waste removal it wil build up and create hair algae out the yin-yang, as well as BIG amonia and nitrite spikes causing your tank to crash.
If you plane to go fish only again for a while longer I would buy a canister filter with NO bio-wheel atatchment. AND RUN GOO DQUALITY CARBON THROUGH IT UNTIL YOUR PROBLEMS CLEAR UP. carbon will saok up all the nasties (chemicals that are left over after the large water change.)

Also what sort or power heads are you using to create flow?
Good flow is VERY critical in marine aquariums as well. There must be enough flow to keep the debris a float long enough mor emost of it to makeit through the intake of the filter and protien skimmer.

YOu should be using at least two STRONG power heads on a 55g tank.

WHat sort of substrate do you have? Crushed shell, or aragonite?
I am sorry if you have already answered this.



Please read up on the net on how to thoughroughly care for a reef tank before you turn your 55g into a reef. You have MUCH to learn before you tackle a reef full on.
Dont take that as an insult, I just want you to have a happy healthy reef.
Read up on filtration, skimmers, substrate, LIGHTING, flow. Then begin to study up on which corals you would like to keep and what they get along with , how they are cared for, and what lighting they need.
After you have soaked it all in and bought the proper equipment, You will be well armed with all the knowledge you need to rear a THRIVING reef.

I hope all of this helps you in some way!
 
Thanks for all of the advice. Like I said I inherited the tank a year ago which was set up as a fish only/live rock tank, and there was no HOB. Also, to clarify, the tank has a good size built in overflow box which flows into a 20 gallon sump where the skimmer & return pump are housed. So, I am not sure where I could even use an HOB.

To answer you question regarding flow, I have a MAG return pump of about 750 gph. I recently added a mini RIO powerhead in the tank which adds about 200 gph.

I house a tomato clown, 3 green chromis, 1 cardinal, 1 cleaner shrimp, mushrooms, fancy polyps, and star polyps.

I add iodine, strontium, magnesium, and calcuim.

I have crushed coral for my substrate.

Again, I inherited the tank from my father in law who never really did much with it except house 2 fish and some rock. Let's just say he's never had any great advice to give, maybe that's why he gave it to me. I've been learning as I go from my LFS, and forums like this. So, any advice provided from you guys is greatly appreciated.
 
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