I would recommend returning that pump if you still can. There is no reason to run a high pressure pump in your system.
Laguna Max Drive 4200 draws 840 watts- Cost to run per month = $66.52*
Laguna Max Flo 4280 draws 160 watts- Cost to run per month = $12.67*
In one year, the Max Drive will cost almost $650 more to run than the Max Flo and you will get roughly the same flow. Even if you are unable to return the Max Drive, the more efficient pump (Max Flo 4280) will pay for itself in just a few months. Get the Max Flo and keep the Max Drive as a emergency back-up pump.
The kicker is that using an 840 watt submersible pump is the equivalent of having a heater running 24/7. The pump might be helpful in the Winter when you need heat, but it's only making matters worse in the Summer. You are already pushing the limits of what those fish can handle temperature wise so you should try to eliminate anything that is adding heat to your setup. An above ground pool in AZ used as a fish pond was likely doomed from the start (as was already mentioned), but the high wattage pump is only making matters worse.
You are in Phoenix, AZ? If so, you will need to heat the pond in the winter if you plan on keeping tropicals. You are going to need some serious energy in order to heat 4,600 gallons.
*Estimates are using the national average cost of electricity which I believe is $.11/KWHr