Outdoor tanks. input welcome

[A.T.T.R]

after minimal attention in the coral prop section i am reposting this here

"Not sure who remembers me but i used to have propsystems located in a garage. long story short i moved. person who was watching the tanks left the door open on the coldest night of the year so some stray cats could stay warm.. went there later in the week and everything was dead.

its been over a year since that happened and am now planning a new outdoor system and would like some opinions.

Tanks are apx 2.5 by 5 ft by 1.5 ft deep fiberglass
our current plan is to burry them apx 1/2 to 1 ft deep by a canal use 500 ft of tubing in the canal to pump our saltwater outandback acting like a chiller in summer months. cover the tank with pexiglass raised about 6 inch above the tankrim for airflow ( or upsidedown and ontop of the tank on cold nights)

we are located in florida and currently the largest issue i see is how stable the canal temps stay during the year. i am going to go take a temp reading tonight since it has been cold the past 4 nights (33 degrees air temp)
"

 

[Beaun]

I would also get a few 500w heaters with a controller for wen it gets very cold out.

 

[username in use]

Id look into a greenhouse with top windows that open and close.

 

[A.T.T.R]

green house is the goal but we want to experiment more with outdoor growth rates then anything and see how feasable this is.
my first attempt cost well over 10 k and was indoors.. could hardly cover the electric bill.

 

[brycerb]

What about open top for the summer and greenhouse for the winter?

 

[A.T.T.R]

the tank will be covered but not to the extent that it will heat much from the sun, also we are in florida . it can be 80-90 one day and 40s at night