are built in overflows worth it?

[zennzzo]

The additional pressure the canister has to deal with when the return is placed at the bottom of the tank is the displacement of the water that is in the return tube (when the filter is turned off)… The deeper the canister/pump is asked to push water below the surface the more pressure/resistance it will have to deal with…
　
As I said in my original post, This does not mean it cannot be done, but it will reduce the flow of the filter and this should be factored in…
　
I disagree with a couple of further points made in the full post I quoted from, but I do not see them as directly relevant to this thread so no need to debate them here…

No more head than the resistance to move the water to the top edge of the tank...

Remember there is pressure from the intake, leading down to the canister, and that will equalize with the pressure needed to raise the water back up to the height of the intake.

24" of head is just that 24" of head, doesn't matter if it is in the tank or in a hose outside the tank...

for example if you had a 20' x 20' x 2' deep tank with a hole in the bottom
and a 1' x 1' x 2' deep tank with the same size hole, the pressure and rate would be the same, the only difference is the 20 x 20 will take longer to drain, but the rate would be the same...

Works the same for head...and that's all the pump has to overcome...

 

[Geoey]

No more head than the resistance to move the water to the top edge of the tank...

Remember there is pressure from the intake, leading down to the canister, and that will equalize with the pressure needed to raise the water back up to the height of the intake.

24" of head is just that 24" of head, doesn't matter if it is in the tank or in a hose outside the tank...

for example if you had a 20' x 20' x 2' deep tank with a hole in the bottom
and a 1' x 1' x 2' deep tank with the same size hole, the pressure and rate would be the same, the only difference is the 20 x 20 will take longer to drain, but the rate would be the same...

Works the same for head...and that's all the pump has to overcome...

Thats pretty basic physics . I would be more worried about having holes drilled in the lower portion of that tank .

 

[zennzzo]

Thats pretty basic physics . I would be more worried about having holes drilled in the lower portion of that tank .

why?

 

[badreverend]

I didnt notice it said to run your return to the bottom of the tank- since there appeared to be some question of overflows not accommodating the bottom of the tank- if you put a decent size return pump in the sump and a either a spray bar or a couple of strategically placed return outlets at the bottom of the tank itll blow (heheh)any sediment up and into the surface skimmer- remembering to drill a relief hole( heheh) at the surface to break siphon in case of pump failure- Ive got a DIY sump under my bare bottom 220g with an overflow on one side and return spraybar at the bottom of the opposite side and there is nothing on the bottom...ever

 

[zennzzo]

I didnt notice it said to run your return to the bottom of the tank- since there appeared to be some question of overflows not accommodating the bottom of the tank- if you put a decent size return pump in the sump and a either a spray bar or a couple of strategically placed return outlets at the bottom of the tank itll blow (heheh)any sediment up and into the surface skimmer- remembering to drill a relief hole( heheh) at the surface to break siphon in case of pump failure- Ive got a DIY sump under my bare bottom 220g with an overflow on one side and return spraybar at the bottom of the opposite side and there is nothing on the bottom...ever

Just curious...
What is the 220g's stock list
and
What is the returns' GPH?

 

[badreverend]

Just curious...
What is the 220g's stock list
and
What is the returns' GPH?

15" black arowana
12"florida
12" congicus
11"endli
10"endli
8"IT
7"IT
7"NTT
5" royal pleco
4or5x 2"-3"bushynose plecos
as for the pump- its a rio 32 HF that I replaced the impeller on this month- so Id say its putting out close to the 1920gph its listed as having
Im sure the bare bottom is also working in my favor-
why do you ask Z? It seems like all of your filters do well too

 

[zennzzo]

15" black arowana
12"florida
12" congicus
11"endli
10"endli
8"IT
7"IT
7"NTT
5" royal pleco
4or5x 2"-3"bushynose plecos
as for the pump- its a rio 32 HF that I replaced the impeller on this month- so Id say its putting out close to the 1920gph its listed as having
Im sure the bare bottom is also working in my favor-
why do you ask Z? It seems like all of your filters do well too

Oh the filters have always done their part, but I recently added rocks to the bottom of my bare bottom tank, because I couldn't stand to look at the debris that didn't make it to the overflow...
and that's with a 3600gph DART pump.
I'm sure it had to be my return location in reference to the overflow box...
Good job, nice stock list...

 

[badreverend]

Oh the filters have always done their part, but I recently added rocks to the bottom of my bare bottom tank, because I couldn't stand to look at the debris that didn't make it to the overflow...
and that's with a 3600gph DART pump.
I'm sure it had to be my return location in reference to the overflow box...
Good job, nice stock list...

Thanks- I dont know where your overflow lies- but mine is in the middle of one of the side walls, with the spray bar on the bottom of the other side- you said you added rocks, but have you tried absolutely nothing on the tank floor? but then again, your problem might be that you have a rear overflow and you dont want the return jets or spray bar up front- if thats the case maybe try return jets on the ground on either side of the overflow and one in each rear corner all facing forward- that would give a similar vortex

 

[zennzzo]

Thanks- I dont know where your overflow lies- but mine is in the middle of one of the side walls, with the spray bar on the bottom of the other side- you said you added rocks, but have you tried absolutely nothing on the tank floor? but then again, your problem might be that you have a rear overflow and you dont want the return jets or spray bar up front- if thats the case maybe try return jets on the ground on either side of the overflow and one in each rear corner all facing forward- that would give a similar vortex

I do have a single overflow box, 20" long and 3" wide,
giving me 26" of toothed skimmer centered at the top of the back.

My returns are centered 24" apart and 8" off the bottom of the tank on the back wall.
I have tried every angle that is possible to get the debris off the "BARE" bottom and that's running at least 3000 gph.

I mean it's not bad, but to me with a black bare bottom with just a little bit of crap looked like hell...That's when I went with the Black River rocks...


This is a shot of the plumbing when I was putting it together, before blacking the back panel. Those are 1.5" return bulkheads, that are threaded on both ends. It was easy to screw in elbow's on the inside, and aim them at every conceivable angle...

 

[badreverend]

3000 gph is plenty I would think, but maybe the 1 1/2" returns arent allowing enough pressure to flush the crap up? possibly step down the return to 3/4"? and the monster return pump is at full current? its not throttled down at all?