Upgrading to bigger aquarium

[Smokeshow]

About 6 months ago my 75gal reef aquarium started leaking from one of the bottom seals. I transferred all the fish and rocks with corals to a 40b. I'm currently building a 200 gallon plywood aquarium. It will be 76x30x24". I can only mix 55 gallons of saltwater at a time. What would be be best way to transfer the rock/corals to the new tank? Have 80lbs of caribsea sand from the 75gal. And another 80lbs of dry special grade. Should i fill it 3 times to around 150 gallons with a heater and wavemaker then add the rocks and sand and fill it the rest of the way. Using as much of the water from the 40B as i can. Still about a month away from completing.

 

[SpyC]

Is rhere a sump? If yes, I would completely fill upbthe dt, transfer fish and rock, then use the remaining water to top off the sump. Put some of the old sand into the dt as well.

 

[Smokeshow]

Reusing the 55gal sump. It's connected to the 40B right now. The old sand is dry. Going to give it a good rodi rinse before putting it in the new one.

 

[Smokeshow]

Been thinking about the sump. Not sure if the 55 will have enough space in case of a power outage. So I've come up with possible 3 options.
1st: get a 75gal from peco and glass for the baffles. Total cost would be around $150
2nd: make one out of plywood. 48x22x16". Would be about 65gal. Total cost around $120. Would need to get more pond shield.
3rd: build one out of acrylic. Same dimensions as the plywood. Using 1/4" cast acrylic would be around $450. 3/8" would be $520. Have limited experience with acrylic.
Option 1 would be the easiest to make but this the sump going under the stand the height of the 75 would make it difficult to work on.
Getting the materials tomorrow to start on the tank and stand.