New SW tank

Question
I just took the plunge into the hobby after 3 years of debating and saving :).  Tank has been running for about 6 weeks now.  At week 4 I added 3 blue chromis and they all died within a few days.  All water parameters were normal.  At week 5 I added a clownfish.  (He appears to be doing well).  When I left my house this morning the tank was clean. When I returned a few hours later there was brownish algae everywhere! Is this normal?  How do I get rid of it?

Tank is 55 gal-30lbs live rock-60lbs aragonite live sand-canister filter-protein skimmer-

I have been keeping the lights on for about only 5 hours per day for the last week.

Another ques..the temp in my tank keeps fluctuating between 77 and 84F.  How do I stabilize the temp?  I plan to add soft soft corals in a few months.

Answer
Hello,
Try placing your heater near the middle of the tank.  Just place towards the back of the tank as well.  This will help it to stabilize the temp. A 2 degree spike is normal. You do not have a power head so this may be the reason as well.

I feel that you may have a phosphate problem and your lighting needs to be on around 10-12 hours per day.  Too much phosphate will cause a red/rust colored algae to grow  everywhere..within hours too

1. Check your phosphate levels.  You can buy some phosphate remover that is placed in the filter. Or they sell filter pads that remove it too.
2. try a 10 to 12 hour light schedule
3. your may have a lot of dissolved organics in the tank so cut back on the feeding schedule to just once a day for a week.

Good luck
Todd