If I use a 3 bag sandfilter and fill it with bio balls etc. What size pond would this be a suitable for as a bio filter. The 25lt Ultra Zap's are fine for 12000lt's, so this sandfilter bio should then be suitable for 30000lt's...or are my calcs wrong.

thanks

Instead of bio-balls I'd advise you to use koi sand. The koi sand I'm using in my "bio-sandfilters" is 5 - 7mm.

thanks Chris, I do have my mechanical setup with 3-5mm koi sand already, would this suggestion of your still be suitable as a bio filter? Would definitely be a hell of alot cheaper.

Please also advise on what size pond 1 filter with this setup would be suitable for.

I am planning on extending to about 22000lts and want to know if 1 sandfilter with whatever I decide to go with inside, will be suitable as a bio filter.

thanks

Hi Cliff

If your water has already been "cleaned from solids" it should be fine IMO.
because using the sandfilter casing as a bio filter has some advantages in that you can backwash it from time to time.
I would consider to put some alfa grog in maybe with the bio balls and you should have a good bio filter.

"Off the record"
Remember that this is not a presurised system, only a enclosed system there is no additional pressure in sandfilters.

Hi Neville,

I'm abit confused by you saying it's not a pressure system, I am under the impression that it is a pressure system as it is a sealed enclosed system so is forced through an outless by pressure??

Also, what would the difference then be in pond volume between a 100lt enlosed system and a 100lt pressure system, would the 2 system only be suitable for different volume ponds??

Hope I'm coming across clearly

That will be more than sufficient as a biofilter. I have three 3-sandfilters on my selling ponds..... 2 running with 5 - 7mm koi sand and the 3rd running with normal 1.1mm pool filter sand just to "'polish" the water. It's working great.

Chris, so do you have your 1.1mm after the 2 sandfilter with 5-7mm?

Obviously if it was first with the 1.1 it would clog up more frequently. How do you do your backwashing? I know as a bio filter you should not be backwashing or cleaning it too frequently.

Sorry for all the q's

That's correct, two 5 -7 mm filters before the 1.1mm filter. All is working great. I backwash every 5 days exactly. I open every filter and stir the sand until the water comes out clean. You won't have a problem with cleaning the "bio-sandfilter" often because you're using pond water.

My main pond has been running the same way for about 6 months and I haven't had any problems.... I prefer this setup by far, but that's just my opinion.

Hi Cliff,
This system that Chris is using is probebly the best system ever to use. You wont get better and it is cheap, very cheap.
If a sand filter was a presurised system he would get no water at the other end. There is no system that will deliver cleaner water than this. I would just, and only if you like add air to make it easy to backwash and save water.

Great system Chris

Just in case this is misunderstood:

Quote :

You won't have a problem with cleaning the "bio-sandfilter" often because you're using pond water.

Meant to say that you can clean regularly without doing much damage to the bio-filter because you're using pond water and not "clean" water.

Thanks Neville for your comment. I've used the other filter setups and I prefer this setup by far.

Hi Chris
You are correct, that is what I asumed, also your bacteria will not be washed away completely just slightly reduced and will recover very quickly again.

Sounds like a solution!!!

I just want to use the 2 sandfilters tho, would that still be ok for a 22000lt pond?

My Idea is...

From pond to...
0.75kw pump to
1 x sandfilter (mech) with 3 - 5mm koi sand to
1 x sandfilter (bio) with 5 - 7mm koi sand to
1 x 55w UV light
back to pond

or should I have my sandfilters the other way around??

thanks again

It's fine for 22000l. I would just swop the filters around. 5 - 7mm sand before the 3 - 5mm sand. If possible, try to add a small 2-bag filter with 1.1mm pool sand. This will polish your water brilliantly and also trap more of the smaller dust particles. If you don't want to get another filter then just add 1.1mm sand to the second filter.

Chris is 100% correct. Put the coarse sand first, (same size sand in both also ok). The sand from speck pumps is ideal.
If you can add that 2 bagg filter with pool sand, you will not believe the clarity.

Excellent......so looks like I wont be adding a settlement chamber then.

Either just the 2 x 3 bag filters, 1st with 5-7mm sand and final with 1.1mm sand

or

3 sand filters, 1st with 5 - 7mm sand, 2nd with 3 - 5mm sand and 3rd with 1.1mm sand then UV then back into pond.

Perfect Cliff,

Please let us know once you have installed it.

Should start building in June when the rains have slowed down, so hopefully all in and done by end of June