Hey,

I used the 100-125 gal EI dosing as a base for my 180 and I ended up with the following:

+/- 3.0 tsp KN03 3x a week (N)
+/- 1.0 tsp KH2P04 3x a week (P)
+/- 45-50 ml Trace 3x a week
50% weekly water change with Prime

So for a 240 which is 1/3 again as large as mine, I would add about 35-40% and end up with:

+/- 4-4 1/4 tsp KN03 3x a week (N)
+/- 1.5 - 2.0 tsp KH2P04 3x a week (P)
+/- 65-70 ml Trace 3x a week

However, Vaughnh has more experience than I.

I agree with Vaughnh and think you should dose 100% from the start.......

Your water change schedule should handle any overages....

I would also plant heavily with stem plants or vals at the start as you get things going. You can always replace with something else later......If these plants don't grow well, you know something is not right.

Good luck. Please post some pics!