Setting up a used 450 gallon tank

I just bought a used 450 off of Craig's List for $1000

It's 8' X 3' X 30 inches deep, stand and two 55 gallon sumps with pumps and a ton of bio media.

Now I need to set up the filter system to support monsters!

The tank currently has two overflows on each end. The overflows have a 1.5 inch bulkhead going to it's respective sump. The sumps have a submersible pump but I don't see returns to the tank? It must of been set up with a spray bar system?

To do list:

This tank needs a drain, I hate syphoning! I want the drain to go out to the yard. Good for emergency draining, maintenance, ad-hoc water changes, whatever, it's just nice to turn a valve and drain the tank

I need a drip system to constantly put in 1 gallon of water an hour and I want this to drain out to the yard. No valves, timers, just a simple overflow type system. 1 gallon of new water goes in and 1 gallon of dirty water go out to my wife's roses.

I need some water movement at the lower part of the tank. Currently the tank is set up for just overflows, surface water overflows to the sump and new water is pumped back into the tank through a spray bar. Nothing seems to be happening on the bottom. Not good for monsters because with heavy feedings comes heavy.................

I'm going to put in two closed loops right at the bottom of the tank and direct the flow from one side to the other, sort of give it a river flow. Not rapids or anything.

The sumps need to be connected, I think? What happens if one pump out preforms the other or the tank isn't perfectly level or the closed loop system influences the overflows and one sump gets more water than the other? I'm going to connect the sumps and also use these new holes to put in a drain so I can drain the sumps if I ever needed to. This is a good area to set up an overflow for the trickle system. That way fresh water goes in the tank and sump water goes into the yard.

Bio media installed

This is the sump overflow drain system. I connected the sumps with 1" line then ran it to this contraption. When the valve is closed the water flows up and around the valve. When the water level in the sump reaches the horizontal pipe it flows out to the drain. So the water level in the sump is the same as that horizontal pipe and will not go above that level. Now when I need to drain both sumps I just open the valve and most of the water will drain out.

Okay so far I have the drain drilled, 1.5" bulkhead, right behind one of the overflows. Can't be seen from the front of the tank. I drilled a hole in the side of the house for a 1.5" pipe and connected everything. No more holes in the house so everything draining from this tank and future tanks will be plumed to this pipe.

Last night I drilled 6 more 1" bulkhead holes, I think the actual holes were almost 2" for the schedule 80 bulkhead. Two on the left side and two on the right side for the closed loop system. Two more for the sump returns going into the top of the tank. This tank is 3/4" acrylic, my arms hurt from all the drilling! LOL those of you out there in your 40's understand.

I filled the tank and left it over night and I only have one small leak on the closed loop system. This morning I opened that 1.5 inch drain and smiled! WOW! 450 gallons to the yard in about 10 minutes! Next time I'm going to get a picture of the water leaving the pipe! Going with a drain on this tank was a very good idea.

Now that the tank is empty I'm going to push the tank into it's final location. I'm going to need to shorten some drain plumbing and extend the drain pipe to an area where I can add to it if needed with out moving the tank. Someday I'm going to set up another large tank in that room and I will plumb it to the drain.