Reverse flow under gravel filter

J

Jag586

Piranha
MFK Member
May 28, 2012
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st clair shores
So thinking of doing this with my tank instead of having the water enter the top of the tank and pushing the water to my overflow I'm thinking of putting PVC pipes in my substrate and having the water rise up but here's my questions

How far apart should the holes be? And what size holes?

How far apart should the PVC pipes be? And how many? Thinking of using 1/2 inch PVC my tank is 72x 28 foot print

And should I put gravel down then pool filter sand or just pool filter sand? I was thinking of doing crushed coral between the pipes the a screen then pool filter sand hoping the flow of the water in the crushed coral will up ph then some kind of screen to keep the sand on top


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J

joe jaskot

Dovii
MFK Member
Sep 16, 2011
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Clifton, NJ
The problem with setting up a reverse flow undergravel system is trying to get an even flow of water. The further you run the piping the less flow you get. You have to start with smaller holes closer to the water source and increase the size of the holes the further away you go.
 
Gill Blue

Gill Blue

Piranha
MFK Member
Apr 28, 2011
4,072
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michigan
DSCN4939.JPG
DSCN5028.JPG
DSCN5029.JPG

here my RUGF.
1.25" pvc, 1/8" holes around every 3"-4". I did the math but don't remember what it was, but it came out to about 132 or 128 holes... I had to buy the oddball conectors from a seller on amazon.
I have a laguna 1300 gph pump that works well, but I'd be interested to see how 2000+ gph would work. the 1300 wasn't enough for the larger chunks.
I've since started using rid-x and with that there's plenty of flow.
the stones actually cover the pvc, I have about 3" of substrate, those pics are about half my "gravel".

DSCN4939.JPG

DSCN5028.JPG

DSCN5029.JPG
 
J

Jag586

Piranha
MFK Member
May 28, 2012
1,234
36
81
st clair shores
Nice now I know who to hit up for advice thinking of doing 5 or 6 lines all tied together and starting with holes every 4 inches just need to get a small drill bit then putting crushed coral then sand


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J

Jag586

Piranha
MFK Member
May 28, 2012
1,234
36
81
st clair shores
I was going to lay the pipes down, in between the pipes do crushed coral then do a screen of sorts then the sand so the sand won't come in contact with the holes the water passing thru the crushed coral will help with ph


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Gill Blue

Gill Blue

Piranha
MFK Member
Apr 28, 2011
4,072
118
81
michigan
joe jaskot said:
You don't want to use sand. It will eventually clog your holes.
Click to expand...
maybe, but I'd think it would be unlikely with a reverse flow. however, the sand will work its way though the larger bits to the bottom of the tank. that will greatly limit your flow and probably cause quite a few dead spots. with enough power you might be able to have a moving sand bed...

I don't know if your mix idea will work. if you put your substrate like mine, directly on the bottom, a small particle substrate will need a lot more waterflow and smaller spacing between the holes to work. I saw one guys video on youtube and he ended up with just small sand fountains directly about the holes. pretty cool feature, pretty poor filtration.

my next run I do plan on trying the pool filter sand you can get from Pooltown with a undergravel filter using the blue/white filter pad between the sand and the plate. oddball has had good results that way.
 
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