Tools for working with acrylic?

[thejuggernaut]

What is your intended goal for flow. Up to 1500 gph, you could get away with 1" bulkheads with 1.5" drain lines. I would personally just go with 1.5" bulkheads. There really isn't any down side. I would say to make the external box 8-9" deep, that way you have enough height to get your siphon purged well. Make the external box long enough to put your pass through bulkheads on the outside of your three vertical drain bulkheads. You don't want to have them dumping out an inch in front of the vertical drain lines, or it will impede flow. The goal is to make the boxes small. But if you make them too small, they won't perform well. Make the internal box whatever length you want. The longer it is, the better your surface skimming performance will be. Also, the longer the box, the quieter it is. Make the internal box atleast 1.3" thick from front to back. That gives enough clearance in front of the bulkheads so it doesn't impede water movement. I eurobrace the external boxes for the ones I make for people. Use 2" bulkheads to connect the two boxes together. Even if one clogs, you still have enough room to flow 3000 gph through only one of them. On your internal box, make sure you brace the top so that it doesn't bow any. I have started installing these 3" long braces on my overflows. They are just below the top of the tank, but provide a ton of support. They make the box very ridged, but you still have enough room to get in there to clean it out with a bottle brush when you need. Order an extra set of gaskets for your pass through bulkheads. They go on either side of the glass. The ones outside the tank actually keep the water in the system. The front ones just add a little spacer to keep the internal box off the glass, so you don't get any pressure points if the box isn't perfectly straight. HTH

 

[thejuggernaut]

Forgot to ask if the tank was rimmed or not. If it is you need to add some spacers to the external box so that you can set it off from the tank so it will clear the rim. Allot of people just run the external box lower, but I think that is a mistake. The external box only holds a gallon or two and fills up extremely fast. If it were to have problems purging, or temporarily got a clog, it would have very little time to correct itself before the box would overflow. If you set them level with the rim of the tank, it will raise quickly until it equalizes with the tank water level, then it will only raise at the same speed as the display. It will give the system allot more time to engage an emergency siphon. It is just another layer of safety without any downside.