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#26
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My system is running a quiet one 4000, that given the head height I reckon is probably (according to the graph on the box) pushing 600 - 800 gph. I'm running on 1" bulkheads with 1" drains also. The drain system I chose is a three drain herbie (also sometimes referred to as a bean animal), I realize that you only have two holes, but the third drain is just an extra paranoia measure which I could easily accommodate by just adding an extra hole in my overflow box, so I did it while I had the drill out.. The returns are 1" single up to about the level of the bottom of the tank where it splits and goes up the back of the tank and over the edge, also in 1". I then have some 1" pvc end caps that I've drilled 5/8" holes in to get a bit of pressure behind it (these aren't glued so I cab remove/redrill/replace as whim dictates.. There are some pictures of my set up in the build threads on my sig. They probably explain it far better than I have! The early for the 75 are in the latter parts of the 27 log - and why not, because that makes complete sense! ![]() I found that with the return pump at full belt I still have to close my ball valve somewhat in order to make any flow through the second drain and keep the main one air free, so one 1" with 1" plumbing downstream drain can handle in excess of the required flow from my pump. You mentioned that there were two holes in the overflow box, if one is 1" then you're home free, because your main 1" drain can handle the flow plus some, then your second can also handle it if the main one blocks completely, and a herbie is totally doable.. if the second hole is the 1/2" return you mentioned, then things become more complicated, or you may have to accept that you can't handle the flow if your main drain blocks completely (how likely a complete blockage is I don't know) surely though, it's safer than a single drain.. If you build an overflow box I'd vote for external - I really like mine a lot because it doesn't intrude on the tank at all. I'm so glad I didn't go internal as I'd originally planned. Now if I can only stop the cats trying to drink out of it.. ![]() Either way, I'd be very tempted to get rid of that 3/4" section in your drain, no doubt that would increase your drain flow a lot, and save you throttling back the pump...
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SmallFry's 75 Gallon (Reef Eventually) Build |