new to ATS need addvice

okay i have a mixed reef thats 6 years old the main tank is 90gallons but have a frag tank also plumed in which gives me about 150 total gallons for the entire system.
i feed about a 2 cubes a day but sometimes i skip feedings and some days may feed less,now im planning to install a double sided ATS in sump with its own feed pump
my question how big of i screen should i use?and what lighting options/watts do i need to use?(i would prefer to use the spiral clf for space reasons)and what gph should i run?
thanks

Forgot to mention I do feed 2-3 small silversides to my eels and lion every 3-4 days too ,not sure how to incorporate this in the sizing of screen??
Thanks

Welcome.

I used to feed silversides; try making 1 = five cubes.

Scrubbers are sized according to feeding. Nutrients "in" (feeding) must equal nutrients "out" (scrubber growth), no matter how many gallons or liters you have. So...

An example VERTICAL upflow or waterfall screen size is 3 X 4 inches = 12 square inches of screen (7.5 X 10 cm = 75 sq cm) with a total of 12 real watts (not equivalent) of fluorescent light for 18 hours a day. If all 12 watts are on one side, it is a 1-sided screen. If 6 watts are on each side, it is a 2-sided screen, but the total is still 12 watts for 18 hours a day. This screen size and wattage should be able to handle the following amounts of daily feeding:

1 frozen cube per day (2-sided screen), or
1/2 frozen cube per day (1-sided screen), or
10 pinches of flake food per day (2-sided screen), or
5 pinches of flake food per day (1-sided screen), or
10 square inches (60 sq cm) of nori per day (2-sided screen), or
5 square inches (30 sq cm) of nori per day (1-sided screen), or
0.1 dry ounce (2.8 grams) of pellet food per day (2-sided screen), or
0.05 dry ounce (1.4 grams) of pellet food per day (1-sided screen)

High-wattage technique: Double the wattage, and cut the hours in half (to 9 per day). This will get brown screens to grow green much faster. Thus the example above would be 12 watts on each side, for a total of 24 watts, but for only 9 hours per day. If growth starts to turn YELLOW, then increase the flow, or add iron, or reduce the number of hours. And since the bulbs are operating for 9 hours instead of 18, they will last 6 months instead of 3 months.

HORIZONTAL screens: Multiply the screen size by 4, and the wattage by 1 1/2. Flow is 24 hours, and is at least 35 gph per inch of width of screen [60 lph per cm], EVEN IF one sided or horizontal.

LEDs: Use half the wattage as above. 660nm (red) is best. You can mix in a little 450nm (blue) if you want.

Very rough screen made of roughed-up-like-a-cactus plastic canvas.

Clean algae off of the screen:

Every 7 to 21 days, or
When it's black, or
When it fills up, or
When algae lets go, or
When nutrients start to rise

So would a 10x10 screen work for my tank?

Or a 9x12 ?

Actually small silversides might be only 3 cubes.

So 2 cubes + 1.5 = 3.5/day. Go with 4/day = 48 sq inches = 6 X 8 inches = 48 total real watts = 23 watt spiral with reflector on each side.

I think I'll bump up my feeding a little, so can I do an 8 x8 = 64 total real watts and ill put two 32 watt spirals if they make them in 32 watts?

30 something watts if fine, but don't increase feeding until your problems are fixed.

I got it ....,I'm only having a phosphate issue nitrates are undetectable.
So ill go with the 8x8 watch my feeding for now then when phosphate are in check feed a bit more then
Thanks for all your help
And as far a flow is 280 gph good?

Yes.