Looking to putting a refug under my 75 gallon I'm using an old 20 gallon tank what else should I need I have a protein skimmer already. just need a list after that.
Do you mean you want to add a refugium to your existing sump or you want to add a sump with a refugium?
Check the web, there are useful articles, graphics and even youtube videos on DIY sump. A fuge is a sump intended to keep macroalgae (I add a deep sand bed in it too).
This is what I would do for a fuge: Bubble trap
Take the old 20gal tank and use masking tape and a sharp blade to show where and how you want baffles to be placed. The fuge should have at least one bubble trap, I like placing the bubble trap just before the return pump although some place it at the water entry section.
with 1000LPH [264GPH] (although 750LPH [200GPH] could work) and a head of at least 5´[1.8m].
PVC plumbing parts
3/4" [as minimum, most go with 1 or 1.5"] PVC tube, parts (consider a ball valve to adjust output from return pump). The plumbing could be done with flexible hoses but I've found rigid PVC plumbing quite easy and more friendly towards water flow. A PVC cutting plier makes cutting PVC a walk in the park. Assembly and try everything without using cement, once you are pleased with results, use cement to bond parts definetily.
There are different ways of designing a refugium. I like using 6" deep sand bed to enhance biological filtration, so another baffle would be needed is you go this way to separate the sand bed section from the skimmer, which I like placing just before the bubble trap.
Glass pieces for the bubble wall and other divisions should be cut by someone with expertise. I've found most glass shop technicians to be friendly and charge very little for making this custom cut pieces. Get the edges polished or sanded so you don't cut yourself when handling these glass pieces. Use aquarium safe silicon and masking tape to place them. Be careful to use adequate silicon bed as you work (too little you end up with leaks or even glass piece falling; too much and your silicon will take longer to cure). Allow silicon to cure (I let mine go for five days).
Hope this helps
Not sure I agree with the terminology there. A Sump can house a fuge, but a sump is not necessarily a fuge. A sump is simply a place where the tank's total water volume can be expanded and unsightly equipment can be held. It can also be a location for any filtering media such as floss or activated carbon. Many people, like me, run their refugiums separate from their sump. In fact my sump acts as a sump for both the display tank and the refugium.
The reason for this is that a refugium should have 10x it's total volume turned over per hour. A tank should have it's total water volume turned over 10 to 20 times per hour. If you have a ten gallon refugium then 100 gallons should move over it per hour, yet if it is in the sump and your total water volume is 100 gallons (75 gl tank and 25 gallon sump) then your refugium has a turnover rate of 1000x to 2000x per hour. That is too fast for the refugium to act on the water that is running through it.
thanks. I don't have either under my tank trying to build my own so I can save money