Sup everyone

Recently started with a setup (3 7850-AMD ATI Radeons) with some tweaks here and there got to about 900-100m/hash. A big bonus is that we don't have to pay for electricity in the building so that saves some overhead costs;)

The thing is in the SlushPool, the reward is very low (have like .4BTC so far in 2weeks) which makes me wonder:
-Is it best to upgrade to more power OR
-Switch pool and if so, what are the be determinants to look for-its still a bit confusing for me

thanks a lot for all suggestions & help

BitCoinUnited