Flow rating of my HOB Overflow?
- Thread starter bheron
- Start date
escape2thewater
Active Member
You can get a pretty close "guestimate" by what size the drain pipe is on it. Most 3/4" are around 300-400gph , 1" can be from 600-800gph. No matter who designed it, it can only flow so much water through the drain! HTH.
Kyle
Kyle
bheron
Member
escape2, thanks for the info!
well, in the meantime I actually ran a "wet-run" test of it in my tub! i ran it full for 1 minute and it put out only 2 gallons of water - which looked pretty good until I calculated that at 120GPH? Am I missing something here or do I have a pretty weak overflow rate? I am planning a 75G fowlr + simple inverts. I have two nice powerheads so that should help water flow.
The drain pipe is pretty wide. Havent measured it but its probably about 3/4". It looks like the J-Tube, or maybe the box thats inside the tank, dont pull enough water through.
For my sized tank, I've heard the 5-10 times (375-750gph) should be the optimal turnover rate.
Any thoughts? Will I have to just invest in a proper box?
well, in the meantime I actually ran a "wet-run" test of it in my tub! i ran it full for 1 minute and it put out only 2 gallons of water - which looked pretty good until I calculated that at 120GPH? Am I missing something here or do I have a pretty weak overflow rate? I am planning a 75G fowlr + simple inverts. I have two nice powerheads so that should help water flow.
The drain pipe is pretty wide. Havent measured it but its probably about 3/4". It looks like the J-Tube, or maybe the box thats inside the tank, dont pull enough water through.
For my sized tank, I've heard the 5-10 times (375-750gph) should be the optimal turnover rate.
Any thoughts? Will I have to just invest in a proper box?
broomer5
Active Member
bheron
Can you describe how you set up this wet run test in your tub ?
Did you use a pump or pour water into the inner box ?
Did you just use the faucet to feed the test ?
How was the overflow mounted in this test ?
You said "i ran it full for 1 minute and it put out only 2 gallons of water"
What do you mean you ran it full.
You filled the inner box completely full .. ?
How and why ?
Can you describe how you set up this wet run test in your tub ?
Did you use a pump or pour water into the inner box ?
Did you just use the faucet to feed the test ?
How was the overflow mounted in this test ?
You said "i ran it full for 1 minute and it put out only 2 gallons of water"
What do you mean you ran it full.
You filled the inner box completely full .. ?
How and why ?
bheron
Member
Hey Broomer,
Maybe I didnt run a correct test?
Hmm.
Here's what I did- real lo tech:
Simply held the overflow box/unit under the tub facet (primed it properly).
Then I started the siphon (much nicer to do with clean fresh water!) and the unit started to pull water through the jtube and into the outer overflow box and out the output hole.
So the faucet was the only thing filling the box. I noticed during the test that the box wasnt really overflowing into the tub and if I turned it up slightly it seemed to handle the increased flow withouth overflowing into the tub. When it was running consistenly, I simply slipped a bucket under the unit for exactly one minute. Strange, that it filled 2 gallons right to the mark after the minute.
Maybe...if I turned the faucet on even more it would've worked faster? Hmmm. The inner overflowbox was full the whole time.
???
Maybe I didnt run a correct test?
Hmm.
Here's what I did- real lo tech:
Simply held the overflow box/unit under the tub facet (primed it properly).
Then I started the siphon (much nicer to do with clean fresh water!) and the unit started to pull water through the jtube and into the outer overflow box and out the output hole.
So the faucet was the only thing filling the box. I noticed during the test that the box wasnt really overflowing into the tub and if I turned it up slightly it seemed to handle the increased flow withouth overflowing into the tub. When it was running consistenly, I simply slipped a bucket under the unit for exactly one minute. Strange, that it filled 2 gallons right to the mark after the minute.
Maybe...if I turned the faucet on even more it would've worked faster? Hmmm. The inner overflowbox was full the whole time.
???
broomer5
Active Member
Sounds like a reasonable way to test the overflow actually.
Couple things to consider when doing the test.
1)
The amount of water leaving the drain obviously is determined by the amount of water entering the inner box.
2)
The way these things work is affected by the "difference" of water level elevation between the inner and outer box.
If the inner box is completely full, and the outer box water level is not lower then the inner's - you will not have much differential. In other words - the higher the inner level is "relative" to the outer box water level - the more flow.
If both are near equal levels - flow will stop or reduce drastically.
That's why the inner box most always has the plastic wing nut adjustment.
You want the inner box ( tank side ) level higher than the outer boxes level.
3) You should mount the overflow in a bucket or rubbermaid container - then set this container in the bathtub.
Simulate an aquarium/tank - and then add water to the container and let it "fall" through the teeth of the inner box.
Just holding it up under the faucet may not keep it level - plus it does not allow for the water level to come up to the teeth as it should.
4)
If you can set up the test again, and let it run steady for at least 6 minutes, then multiply by 10 ... I think you'd get a better average.
5)
See if you can get it running so the inner box level is higher than the outer box level - and only then start to measure the drains output.
6)
Ideally the test should be run with a drain hose or pipe of at least 3-4 feet. This is how the unit will be set up on your tank.
The drainline "will" affect how fast or slow the unit functions during your test. You may need to set this test bucket/rubbermaid up on a small stool or rig up stepladder/plywood sheet - to get the test vessle up high enough to allow for the drainline to run down to a 5 gallon "measuring" bucket.
Measure the inside diameter of your U tube, and measure the inside diameter of your drainline.
Post these measurements along with the LxWxH of your boxes.
This will help to determine the things capacity too, and maybe we can figure this out better.
If all of this is too much bother - I would understand completely.
See ya
Couple things to consider when doing the test.
1)
The amount of water leaving the drain obviously is determined by the amount of water entering the inner box.
2)
The way these things work is affected by the "difference" of water level elevation between the inner and outer box.
If the inner box is completely full, and the outer box water level is not lower then the inner's - you will not have much differential. In other words - the higher the inner level is "relative" to the outer box water level - the more flow.
If both are near equal levels - flow will stop or reduce drastically.
That's why the inner box most always has the plastic wing nut adjustment.
You want the inner box ( tank side ) level higher than the outer boxes level.
3) You should mount the overflow in a bucket or rubbermaid container - then set this container in the bathtub.
Simulate an aquarium/tank - and then add water to the container and let it "fall" through the teeth of the inner box.
Just holding it up under the faucet may not keep it level - plus it does not allow for the water level to come up to the teeth as it should.
4)
If you can set up the test again, and let it run steady for at least 6 minutes, then multiply by 10 ... I think you'd get a better average.
5)
See if you can get it running so the inner box level is higher than the outer box level - and only then start to measure the drains output.
6)
Ideally the test should be run with a drain hose or pipe of at least 3-4 feet. This is how the unit will be set up on your tank.
The drainline "will" affect how fast or slow the unit functions during your test. You may need to set this test bucket/rubbermaid up on a small stool or rig up stepladder/plywood sheet - to get the test vessle up high enough to allow for the drainline to run down to a 5 gallon "measuring" bucket.
Measure the inside diameter of your U tube, and measure the inside diameter of your drainline.
Post these measurements along with the LxWxH of your boxes.
This will help to determine the things capacity too, and maybe we can figure this out better.
If all of this is too much bother - I would understand completely.
See ya
bheron
Member
Brommer, thanks, good stuff.
Great idea. I have my 15 gallon rubbermaid that I'll use to simulate my tank. I think its a good idea to completely simulate it and use the output hose, so I'll see if I can prop it up so it flows down.
I hope this will give a more accurate ---and higher --- reading than my 120 gph. I wasn't budgeting for @$130 for a new overflow box!
Thanks,
I'll post the results as well as the measurements of my tubes and box.
Thanks!
Great idea. I have my 15 gallon rubbermaid that I'll use to simulate my tank. I think its a good idea to completely simulate it and use the output hose, so I'll see if I can prop it up so it flows down.
I hope this will give a more accurate ---and higher --- reading than my 120 gph. I wasn't budgeting for @$130 for a new overflow box!
Thanks,
I'll post the results as well as the measurements of my tubes and box.
Thanks!
krux
Member
plug hole. add 1 quart of water. remove plug and count how long it takes to empty. multiply by 4. this is the number of seconds it takes to drain a gallon. divide that number into 60, giving you the number of gallons per minute. multiply by 60 to get gallons per hour.
for example: 2*4=8 60/8=7.5 7.5*60=450
if it takes 2 seconds for your overflow to drain a quart of water, then a gallon drains in 8 seconds. therefore, 7.5 gallons per minute drain, which equates to 450 gallons per hour.
you can go less than a quart, if your final chamber in your overflow will not hold it all, or you can fill the chamber before to the top, then plug the hole, and then dump the water in, so the chamber before has the area displaced.
for example: 2*4=8 60/8=7.5 7.5*60=450
if it takes 2 seconds for your overflow to drain a quart of water, then a gallon drains in 8 seconds. therefore, 7.5 gallons per minute drain, which equates to 450 gallons per hour.
you can go less than a quart, if your final chamber in your overflow will not hold it all, or you can fill the chamber before to the top, then plug the hole, and then dump the water in, so the chamber before has the area displaced.