I have a 9g and found the 200W hydor inline heater does a great job. The thing is really big though! you will need room behind the tank for it.
Great looking scape! Should look really slick once filled in. Great job!
The heater looks huge, but I have 6" between the stand and wall for the CO2 system anyway so I will just need to mount it next to the c02 mixer. All these things should bring down the flow for the shrimps.