the infamous 5 gallon diy canister filter. can it be done????

iamvictor2k said:
i understand that you keep saying that the canister if placed under the tank will have to support all the pressure of the tank and that the canister has to with hold pressure like the tank. this simply isnt true. to prove my point get out your gravel siphon cleaner place a 5 gallon bucket on the floor and siphon it into the bottom of the bucket. if your statement is true then there would be no way that you could put your thumb over the hose and stop the water flow. and i know that i dont have to lift the hose above tank level to stop the flow of the water with my thumb. i have a 55 gallon tank and the pressure from that would not allow my finger to hold it. is this a true statement? please provide descriptive information to prove if not.
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please keep in mind i want someone to make it work and your ideas so far are probably the most sound i've seen. :clap:

i think your thinking is missing something here though.

the can and the lid are pliable... that's a fact.
the pressure gunner is stating is definitely not off by much if it is off.

keep in mind i'm just rounding and rambling here but here me out.

with water about 8 pounds per gallon in a 5+gallon bucket i'd say that's at least 42 pounds of pressure to start with.

e=mc^2 so...

considering the larger diameter hose you'll increase the mass to that of the larger hose. this means your thumb will have to hold back more weight and volume on the canisters hose. that takes care of your m.

then you'd figure out your velocity. this would usually be measured in gph but i think we'd need mph, don't remember. at any rate this number will be represented as c and gets squared.

once c (speed) is multiplied by itself then it's multiplied by m (that weight and volume your thumb would be holding back on your canister hose) to give us e (energy) which would be the force coming into that canister at any point.

i think this could theoretically imo give us about 65 pounds of pressure total.

your pump will be counter acting that weight and when it turns off suddenly it'll all hit the inside walls of your bucket and lid...

given that the water coming into the canister is a siphon that pressure will continue to come after your pump has cut off creating a back pressure relevant to the aforementioned numbers therefore swelling the bucket. once the bucket is swelled and the pressure has nowhere to go we have the old adage and commonly known law of physics "equal and opposite reaction" causing the bucket to bellow. this will not only randomly warp said buckets rim but it will do it in every direction possible. henceforth having a pliable bucket with a pliable top with enough pump strength to return the water to the tank and having it sealed is going to be near impossible to compensate for.

your design is a little different than i've seen though and reminds of point loads and pressure points in automotive parts. the difference that i can see is that you don't have flanged flat areas with the flat head of nuts and bolts fastened through them. plus your gasket may be a little less ridgid and will be resealed a whole lot more often. it will be interesting to see if this works out and i hope you the best.

now, of course all that is assuming it'll be under a stand. if it's level i'll have to agree that the pressure will be less substantial. the reason being here is that the water pushed out by the pump will not be as choked by the resistance and the fact that water flows down naturally until it makes a somewhat level puddle with a nice meniscus. beings that the two surfaces could be level it will not have a natural propensity to migrate towards the bucket due to gravity. this also releases tension of back pressure created by a sudden stop of a motor since gravity alone would barely be a factor. not only that but keeping it higher probably leaves for a pocket of air to give and let the bucket flex instead of water which is pretty much a given volume in terms of area. in other words for the bucket with no air in it to flex the water has to go somewhere.

if you pick things apart like gunner does theres a lot to think about. he's taught a lot of ac'ers a few tricks and always goes into the how's and why's and we appreciate that. i know i do whether he's right or wrong. when he's right we all learn something. when he's wrong someone else teaches him and henceforth the rest of us paying attention learn something.

once again, i wish you the best and i'm definitely keeping an eye on this. at the same time gunner's a smart cookie so i'd give what he says some thought and consideration.

hoping for the best...
dun
 
iamvictor2k said:
i understand that you keep saying that the canister if placed under the tank will have to support all the pressure of the tank and that the canister has to with hold pressure like the tank. this simply isnt true. to prove my point get out your gravel siphon cleaner place a 5 gallon bucket on the floor and siphon it into the bottom of the bucket. if your statement is true then there would be no way that you could put your thumb over the hose and stop the water flow. and i know that i dont have to lift the hose above tank level to stop the flow of the water with my thumb. i have a 55 gallon tank and the pressure from that would not allow my finger to hold it. is this a true statement? please provide descriptive information to prove if not.
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The same reason your able to stop the water under your tank using only your thumb over a very small hole is the same reason you are able to lift a 2 ton car using your thumb to manipulate a very small small piston on a hydraulic jack.

Remember your thumb isn't holding the entire gravitational weight of your tank or a car, but rather only a vary small fraction of the hydraulic pressure exerted by gravitational weight per square inch, multiplied by the relative surface area it is acting upon. All your doing is holding back a very small fraction (less then 1 square inch) with your thumb in only one direction, while the lid, walls, and base of the canister have a much greater multiplied load in excess of 500 X square inches pressing against it in all directions.

This is what basic hydraulics is all about and which to be explained is beyond the scope of this thread. So you will just have to take my word for it.;)
 
I'm not convinced the that the bucket will have to withstand the total water pressure of the tank. It will arguably have to withstand the force of the full 5 gallons of the bucket plus the volume of the input and output lines.

Maybe this pressure is enough to case the lid to fail. One way to find out!

I can't wait to see what happens.

BTW...If the pressure is too much for the bucket, you could use as a wet/dry filter. The bucket would not be sealed in this case and therefor reducing the pressure on the bucket.
 
You are going to have approximately 8 PSI pushing against the walls of the bucket (trying to distort the bucket to a larger diameter) with an additional 4 PSI forcing up on the lid. The amount of force added to the full bucket is a direct correlation to the water in the column, not the tank.

For instance it could be a 10000 gallon tank of a 50 gallon tank. If the hose hieght and distance were the same in each, so would the PSI. A more rigid top at least at the points were the anchors are would help distrubute the pressure to maintain the seal. Otherwise, perhaps a few barbel wieghts of the right size.......
 
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with water about 8 pounds per gallon in a 5+gallon bucket i'd say that's at least 42 pounds of pressure to start with.
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That has not a bit to do with the pressure exerted on the lid. That weight is sitting in the bucket.

The pressure exerted on the lid is the difference between the incoming water pressure and the pressure that is released by the exit hose from the bucket. Add to that result the head pressure from the bucket to the tank.

In example,

If the pump sends is water at 35 psi, and the exit hose out of the bucket releases 10 psi, but the hose head pressure adds 5 psi, then the psi on the lid would be 30 psi aggregate.
 
That has not a bit to do with the pressure exerted on the lid. That weight is sitting in the bucket.
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This is correct, however, it does factor into the seal of the lid, how much depends upon the rigidity of the bucket side walls. If you have X amount of pressure exerted on the side walls of the bucket, and this pressure distorts the shape of the bucket in any way, it still acts against the integrity of the seal of the lid.
 
Ok, the thought that the canister would have to hold up the entire pressure of the tank is absolutely WRONG! The only way that applies is if the canister was plumbed into the bottom of the tank. It's not. If both hoses reach the top of the tank, only the head pressure caused by the water in the hoses is exerted when the pump is off. And the pressure of the pump and the head pressure when it is on.

http://scubageek.com/articles/wwwparad.html
 
nc0gnet0 said:
This is correct, however, it does factor into the seal of the lid, how much depends upon the rigidity of the bucket side walls. If you have X amount of pressure exerted on the side walls of the bucket, and this pressure distorts the shape of the bucket in any way, it still acts against the integrity of the seal of the lid.
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The bucket is a cylinder. It's not going to distort in any way as long as there is no compromise to the wall integrity. The pressure against the bucket walls is equal all around.
 
Ok, the thought that the canister would have to hold up the entire pressure of the tank is absolutely WRONG! The only way that applies is if the canister was plumbed into the bottom of the tank. It's not. If both hoses reach the top of the tank, only the head pressure caused by the water in the hoses is exerted when the pump is off. And the pressure of the pump and the head pressure when it is on
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This is correct, that is what I refered to as "column"

The bucket is a cylinder. It's not going to distort in any way as long as there is no compromise to the wall integrity. The pressure against the bucket walls is equal all around.
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Thats not entirely correct. Your assuming that all of the side walls are "exactly" the same. Differences in material thickness will occur and thus you will have your compromise. Plus, you still have two forces that are in some way opposing each other, albeit at right angles. If you don't beleive it distorts the bucket try this, measure the diameter of a empty bucket at the top rim. Then fill it with water and measure it again, you will find that the bucket does indeed flex. Even a millimeter is significant when your dealing with a water tight seal.
 
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