Need help deciding on filtration

[BGJ223]

I have heard the required flow maximum should be no bigger than 2000~2500 gph. Otherwise, the force of water will displace the stone layers inside the filter. Same applies to your air compressor, be careful. If you're air compressor is too strong, then it will displace the stone layers inside the filter. When the layers become displaced, then your sand can possibly fall to the bottom of the barrel. You just want a nice simmering, low boiling of air coming out of the top. A good youtube video on what it looks like in action, Cleaning Sand Gravel Filter. This is why you only want a 1 hp blower. A 2 hp blower or a shop vaccuum will likely be too strong; so you will need to make a relief valve that will allow you to gradually add the air into the barrel. Personally, for flow rate, I think slower means better fine particulate filtration. I have 2 that are buried where I have a valve that only around 1800gph goes through each of them; the unfiltered water goes to my fountain or waterfall.

I understand the max of 2500 gph, but what is the minimum that can be used?

 

[Dave 54]

Are your filters vortex style filters ? if so sand is out you dont need it at all just the Jap matting ( or equivulent ) for one you'd never be able to clean the sand or stones , for two as you opened up your slide valve at the bottom youd loose it all .
The airstones the jap matting plus whatever you put on top of the matting will suffice , I have a large bag og zeolite in one another bag in the next this time with lithaqua the other also has a few sponges over the zeolite whilst the other has filterwool sheets it then goes via two 2" pipes into the bio filter my pump is an Oase 3500 , now I think thats litres per hour but cant be that sure
The first vortex is washed through weekly washing all the fish detritus away to drain.

rgrds

Dave

 

[BGJ223]

Are your filters vortex style filters ? if so sand is out you dont need it at all just the Jap matting ( or equivulent ) for one you'd never be able to clean the sand or stones , for two as you opened up your slide valve at the bottom youd loose it all .
The airstones the jap matting plus whatever you put on top of the matting will suffice , I have a large bag og zeolite in one another bag in the next this time with lithaqua the other also has a few sponges over the zeolite whilst the other has filterwool sheets it then goes via two 2" pipes into the bio filter my pump is an Oase 3500 , now I think thats litres per hour but cant be that sure
The first vortex is washed through weekly washing all the fish detritus away to drain.

rgrds

Dave

Not vortex style, I will be using 55 gallon drums.

 

[crsublette]

I understand the max of 2500 gph, but what is the minimum that can be used?

Never thought of asking that. Good question. I do know slower the better but I do not know of any ill affect that would appear when flow rate is too slow, not saying there is none.

I know the S&G filter is a very crude version of a type of reverse osmosis system in third world countries used to purify water and they acheive this with extremely slow flow rates and of course different sand and bacteria materials.

I know the layers of each rock also must be thick enough so that the smaller layer above it does not fall through. Since a higher flow might not be used, could the rock layers be reduced to 2" without the smaller layer above falling through? I don't know.

Also, I would think the water flow rate somewhat helps the blower when purging layers. Would the purge be affected with a lower flow rate? I don't know.

Good question.

 

[BGJ223]

Never thought of asking that. Good question. I do know slower the better but I do not know of any ill affect that would appear when flow rate is too slow, not saying there is none.

I know the S&G filter is a very crude version of a type of reverse osmosis system in third world countries used to purify water and they acheive this with extremely slow flow rates and of course different sand and bacteria materials.

I know the layers of each rock also must be thick enough so that the smaller layer above it does not fall through. Since a higher flow might not be used, could the rock layers be reduced to 2" without the smaller layer above falling through? I don't know.

Also, I would think the water flow rate somewhat helps the blower when purging layers. Would the purge be affected with a lower flow rate? I don't know.

Good question.

You are correct, this method is used in the 3rd world countries. The major difference is the water enters from the top and gravity pulls it through the layers of sand and rocks. So I would imagine flow can be very very low and you still get great performance. But in the pond application, will the slow flow impact clean outs.

I also have wondered how possible it would be to do via gravity feed from the bottom drain. I know the layers will restrict flow, but by how much???

 

[crsublette]

I also have wondered how possible it would be to do via gravity feed from the bottom drain. I know the layers will restrict flow, but by how much???

YARGH ! I THOUGHT SO !! ... Heh, sorry, not in response to you, but in response to my terrible memory.

An example of a gravity fed S&G filter.

Yeah, gravity fed S&G filters have to be much bigger if you want to have a higher flow rate out of them.

 

[crsublette]

Hey BG, I don't know if it is something you're interested in but it does save electricity, thus saving money. If you are doing any gravity fed systems that needs a little push between the SC and Bio, instead of using another pump, then you could think about using an airlift approach to move the water.