Starting a 75 Gallon soon - Got questions

[jayjeep]

Update:
Haven't really had much progress. I was supposed to but a 30 gallon long tank for a sump but the guy didn't show up. Still working on that. I replaced the silicone in the 75 gallon tank and it is currently being leak tested. Its been filled since Monday and no leaks so far.
I'm currently researching sand and was looking at CaribSea Dry Aragonite. I was thinking of using a mix of Aragamax Select (0.5-1.5mm) and the Seaflor Special Grade Reef Sand (1.0-2.0mm). I plan on getting a diamond goby or something similar. What do you guys think about that combination of sand size?

 

[jayjeep]

I just bought 80# of Seaflor Special grade (1-2mm) I think I will get another bag of Aragamax select (0.5-1.5mm). Is this going to be a good size sand for a diamond goby and other sand dwellers/sifters???

 

[jayjeep]

Here is an image of what I am thinking for the plumbing for my sump/refugium. The chamber in the middle is the return. I think I will try the herbie system here. Do I have the valve in the right spot? My understanding is that you reduce the flow on the main drain enough to get the water level above the standpipe, so no air gets in.
The top valve will be a gate valve and the valve to the refugium will probably by a ball valve. All plumbing will be will be with 1" PVC. Unions at the bulkheads and pump.

 

[snakeblitz33]

The gate valve you mentioned on the main drain line goes after the T off to the fuge, not before. Consider using a union and a gate/ball valve on your return pump as well. I use unions wherever I can, just incase I have to remove the sump pump - I got a union there. When I have to remove the entire sump tank, I can just disconnect some unions and I'm good to go. It makes things a little easier.

 

[jayjeep]

Would it be better to put a gate valve in for the refugium if it comes before the gate valve to the skimmer?
I don't really understand why the gate valve would come after the T. What difference does it make? Does anybody have any experience with doing it both ways?