So does an up turned elbow. Not a lot, but its there.<a href=showthread.php?s=&postid=12495021#post12495021 target=_blank>Originally posted</a> by das75
Been playing with a Herbie type drain on a 33g with no overflow chamber, just a pipe coming up off the bottom of the tank. Seems to work okay and was silent.
See no reason why couldn't have the bulkhead on the side near the top then with an up-turned elbow.
As pointed out though, a overflow does give that surface skimming.
If its just a hole in the back (bulkhead) with a horizontal exit flow, I highly doubt you have good or any surface skimming, since the physics of the design say that you wont. I've set up many systems like this and they dont skim. You have to have a vertical drop. Even my 65G fuge just has a hole in the back as you call it. It had an accumulation of film on the surface until I added a simple overflow box that provided surface skimming. It cleared up in less than 1 hr.<a href=showthread.php?s=&postid=12500056#post12500056 target=_blank>Originally posted</a> by amehel0
well on my90 the holes are abot an inch off the top and it skims the surface. i just dont get why people use them there more hassle then there worth