melev's HOB overflow queston

[rbrusletto]

Hey guys -

I'd send melev a pm, but figured someone else might be able to tell me the answer sooner...

I've built the overflow box to melev's specs on his DIY site, I'm sure some of you are familiar with his great work. The overflow box works GREAT, I have a few air bubble though, which is the only thing that makes me uneasy.. now heres the question.

simplest way to do this is w/ a maxi jet + airhose correct? that way, any excess air in the upper part of the overflow is removed automatically, keeping the overflow from loosing suction. My problem is, my MJ400, isn't pulling any air out.. so:

Are the MJ400's powerful enough to do this, or do I have a good reason to add some extra flow to the tank and inherit another mixing pump? Currently I've got two MJ supplied airhoses connected together with a little connector(what you would normally attach the air valve to), one side is into the maxiet water inlet, the other to the overflow, stuffed up to the highest place that catches the most air..

 

[supateddy]

I can't say for certain whether MJ400's are strong enough or not. I can tell you I built one of these overflows, and our MJ1200 moved the air out pretty slowly.

To get around the problem, I ran an airline from the overflow to the inlet of the MAG5 sump return pump (which was also talked about on Melevs page, I think.) The suction from the MAG clears the overflow of air pretty well.

 

[rbrusletto]

oddly enough thats the return pump I have, though I got used from a friend, with no extras, is there a mod that I could do this way, I've got a good distance of airline tubing.

 

[manderx]

you'd be better off to hack it apart and use a u-tube to connect the inner and outer boxes. read any thread on CPR boxes to see what all's wrong with this design.

 

[rbrusletto]

manderx, I see the basic thoery is that, due to the added area, the velocity of the water is slower, causeing the bubbles to get in the "U" of the overflow. If you have a sure fire way of getting the air out, then really whats the difference? same thing as the smaller area u-tube, with some extra suction force from the mag 5(which is already the return pump), if the pump fails, the water stops. Common logic would say, if you have a system like this, you wouldn't want the water to overflow the display tank, and would build your sump accordingly, namely a smaller return reservoir, with less volume than that of the extra space in the display tank when the system is running. Considering I top the water off daily, and there is less than 1/4 gallon lost per day would be fine. Granted, this is a workaround, but hey so far this project has cost me all of $24 + tax. which make the whole project possible..

10$ 10gal tank from wal mart
9$ worth of acrylic @ ACE HW for the overflow box
5$ for the bulkhead on the overflow
extra acrylic leftover from free 75G tank for baffles in the sump tank
free mag5 from friend in the business(needed a little cleaning to get it running)
extra plumbing from free 75G tank.

 

[manderx]

If you have a sure fire way of getting the air out, then really whats the difference?

but you don't. nothing is surefire, especially this. the airline will clog. there are countless threads about this in respect to the CPR (which is the same thing). i know you aren't going to believe me, so do the search and see what people who've used the CPR have to say.

a u-tube is what, 3-4 bucks? and if you're too cheap for that you can use PVC.

 

[rbrusletto]

wow... maybe I'm seriously off base on the cost of u-tubes. lfs sells them for $20. probably because they're trying to sell their overflows boxes. I'd looked @ lowes and HD on several occasions without any luck. I've never liked overflows in the first place... they scared me, hence setting up the sump the way I have, in case suction is lost..

 

[dhnguyen]

<a href=showthread.php?s=&postid=10574356#post10574356 target=_blank>Originally posted</a> by manderx
you'd be better off to hack it apart and use a u-tube to connect the inner and outer boxes. read any thread on CPR boxes to see what all's wrong with this design.

Yup.

 

[lakee911]

Use an aqualifter if you still want to use it. That's what I use...*gulp*

 

[lavith]

that melev's HOB overflow based on CPR overflow box doesn't work. Too easy for it to fail => water on floor