that makes sense...now what if I dont have a drilled tank and just use an overflow box? anyone have an overflow box and what is your experience with it? Can you make an overflow box. I imagine you can but I want to do the research before I attempt such a feat..I have also hear of ppl drilling the bottom of their tank to make it quieter...to me this sounds absurd but maybe I am mistaken. Any information on this concept as well?
:bowdown::bounce:
Just drill it. You'll be so happy in the end. I just did it for the first time and it's so easy. I swear, anybody can do it. Why drill? Because it's fool proof.
It's pretty easy to figure out how big a pump you need. I think you should decide how many gallons per hour you want flowing through the tank first. One you know how much you want flowing, start looking at pump specs. Look at the head height. Most return pumps are goiong to have to pump water uphill between 4 - 6 feet to get the water back into the main tank. So check the head pressure on the pumps and get one that matches the flow you need in the tank.
Let's say you wanted to drain between 900-1000gph. You get a pump that will do 900-1000gph at 4' of head - or whatever your height happens to be.
So now you need to get a big enough bulkhead on the back wall of the tank to flow that much water back OUT of the tank. If you're dumping it into the tank from the return pump at 900-1000gph then you need to also be able to DRAIN it out that fast too + a little cushion IMO.
Check this flow chart:
Bulkhead Flow Rate Art
Here is a calculator to account for pipe bends (90's 45's and other fittings)
http://www.engineeringtoolbox.com/pvc-pipes-equivalent-length-fittings-d_801.html
So figure out how many 90's and other fittings you'll have in the system. Each turn or fitting slows down the water flow.
Looks like you'll need a minimum pipe size of 1.5" to flow 900GPH but if you jump up to a 2" pipe, you could potentially flow up to 1200-1300gph. That's the size I would get in that scenario. Over sizing your drain line out of the tank won't hurt you. Just don't go crazy and up the size by 2 whole pipe sizes. Jump to the next size up if your borderline.
You can buy a cheap glass hole bit from here:
Diamond coated ... : welcome to richontools.com
Look at Hole saws 11-60mm or the other one is 61-121mm.
All you need is a cordless drill and somebody to pour water on it while you drill. This was my first time so I was really nervous. This was EASY. I drilled my 2nd hole in about 30 seconds.
Part 2:
After you get the holes drilled, slap the bulkhead in there. Put the rubber washer INSIDE the tank - not outside. Tighten the nut with your hand as tight as you can get it. Now use a giant pair of pliers or a pipe wrench and tighten it 1/4 turn more. Stop. That did it for mine. Neither leaked and the glass didn't crack, so good enough.
After you get the bulkheads installed, take some aquarium silicone and glue the overflow box inside the tank. Support it with tape or stack some books up beneath it to hold it in place. Or use tape AND books.
You know your 2" bulkhead will drain up to 1300GPH, so find an overflow box that will flow that much through the teeth. There are calculators that will tell you how many inches of overflow teeth you need and how large the box must be to flow out the 1300gph you want. Search wet web media again. There's all kinds of things that will tell you how to size an overflow box with the teeth or grates the right height and the right spacing. You can buy overflow boxes from Bulk Reef Supply that are black acrylic like this:
Large Overflow Box For Back Drilled Tanks - English
That way you have enough drain and overflow box to do about 20% more than your pump is actually pumping back into the tank.
I found out that most skimers will need between 8-10" of water depth to work right. Seams to be an industry standard. So your first baffle in the sump is 8" tall or 10" tall if your skimmer needs that much water. Just research your equipment first.
Go to Melevs site for acrylic sump designs. You can get all kinds of ideas on how to do the layout on your particular sump. Then come and ask us where and how tall each baffle should be after you settle on a design and sump size.
Melevsreef.com | Acrylic Sumps & Refugiums
Design your sump and plumbing around the pump. The first thing you do is size the pump for the water you want flowing through the whole system. Then from there, size the bulk heads and plumbing. Then decide how big a sump you need to flow that much water.
I found that I probably spaced my baffles too close together. I only have abnout 1" spacing on my baffles and I should have been closer to 1.5" or even 2" spacing. That slows down the water moving through the baffles. When the water moves slower, the bubbles get caught instead of moving into your sump. Thats what baffles are for. They stop bubbles from passing through those 2 or 3 dividers so when the water gets to the return pump there's no bubbles for it to suck up.
When you unplug the pump, the water in the tank will continue to drain out of the tank until it gets below the teeth on the overflow. Then the tank will stop draining. Unless you have the return line from the sump under the water line in the tank. If the return line is under the level of the teeth on the overflow, then it's going to siphon backwards through that line, through the pump and into the sump -- until the tank finally drains enough that the return line sucks up air and stops the siphon. This is where you need to make sure you put a hole in that return line. I drilled a 1/4" hole in my 1.5" return line. It's just barely under the level of the teeth on my overflow. As the water continues to siphon out and lower the tank level, it eventually begins to suck air through the hole in the pipe and that breaks the siphon.
