brewery chiller help needed

Hello all! I did some mechanical work for a new local brewery. The stacks and burner for a brew kettle. The guys involved in this project have a packaged 5 ton chiller unit that was used to cool aquariums. This unit was stored outside and was frozen. They got it for free and where hoping to repair it. The refrigerant to water heat exchanger is made of stainless steel and pvc. The pvc was cracked beyond repair.

Now all I have is a 5 ton condensing unit. The idea now is to submerge copper coils in a large tank of water (only running around 40 degrees F). They question is how much copper and what size. I'm thinking of doing 4 feed off the txv into 4 coils of 1/2 in. copper 50 ft long. Then manifold back into a 3/4 suction line. All this coppers is going into a 150 gallon tank. That has a 1 hp pump flowing water through the chiller loop.

It's just to get them by until they can get a pro unit.

Thank you,
Jake