bio filter in waterfall?

[JayDogg]

Ok, the pond is built, time to start the bio filter! I'm hoping to use the waterfall for this. It has a large basin (16" x 18" x 24" = 6912 c.i.), which I believe is around 30 gallons (6912 c.i. x 0.00433 gal/c.i.). Below are a couple pictures that should help show what I'm dealing with:



The first pic shows the amount of water flowing over the falls. The pump is rated at 3500 GPH and there isn't a lot of head, so that's probably pretty close. The second pic shows the inside of the basin. I shot it from behind the falls, so the output is at the top of the pic and you can see the inlet at the bottom. You can also see some concaved spots (front and back) and ledge where a structure can be placed. I got this thing for free, so I don't know much about it, but it seems to be designed for an internal structure.

The basin has basically three sections. I'm hoping I can leave the lower (narrower) area to collect solids and build a platform where it widens to the second area. Then filter media would sit on the platform and fill the basin to the upper lip. Then I'd cover it with another grid and place some rocks and maybe plants on top to hold the whole thing in place.

So for starters, I have a few questions for all the experts out there:

1. Is the size large enough to support a sufficient amount of media? My pond is roughly 4000 gallons, I also have a Savio Skimmerfilter (gets the big stuff), and a small UV filter (sized for 1000 gallons). The UV filter is T'ed off the pump output and flows out as a separate little creek.
2. Is the flow rate of 3500 GPH too much for a bio filter to work? There's a lot of current in the basin but I can't divert significant flow to a separate filter without taking away from the waterfall.
3. I can't add a dump valve because the bottom of the basin is below ground level. I can vacuum it out with my Shopvac, but is this a problem?

Thanks in advance for the help!

 

[koiguy1969]

WELL LETS SEE HERE 3500 gph is too much for your filter. but all is not lost...you can use your basin filter run 1000 gal per hour thru the filter and the rest of the flow can be plumbed to enter the top of the filter and just flow out the weir. your falls doesnt lose any flow and you still get the circulation and aeration . i would still add a diy filter in series with the waterfall basin.

 

[JayDogg]

I like the idea of integrating the bio filter into the basin, but how do I divert all but 1000 GPH around it? Can I just build a filter box that doesn't completely fill the basin and assume enough flow will go around it? I could also add it filter in-line with my existing UV, but is 1" flexible hose is large enough to get 1000 GPH? You can see it in the picture below:



The input is T'ed off just after the pump and the output is buried to the left of the unit. It runs about 20' around the side of the pond and flows in as a little creek.

 

[koiguy1969]

i have one input flowing thru the filter (upflow filter) and the other just pumps into the top of the filter to flow out with the filtered water. its that simple!

 

[KennethO]

A flow of 3000+ in a basin that small will not allow hardly any solids to settle if any at all. Pretty fast for bio too and of you cut it back to 1000 you'll lose that nice falls action. Then again you said the UV T's off at the start so how much is diverted to the uv? 50/50? Then it would be more like 1500gph. If it was possible to place the UV/canister filter before the falls, then you could use the canister as a prefilter and place bio media in the falls. Being prefiltered, it doesn't need a settling area so you can stuff it full of scrubbies or bio balls.

Edit: And yes, 1" can handle 1000gph. 3000-4000 is only 1 1/4".

 

[JayDogg]

I would guess no more than 500 GPH is diverted through the UV. I can adjust the split with a ball valve before the falls (restrict flow to falls and push more to UV). I can probably divert up to 1000 GPH without hindering the falls, but the UV manual says the max flow is 500 GPH. Is that adequate for the bio filter? It's all pre-filtered by my Savio skimmer, which contains a huge (coarse) filter pad.

 

[koiguy1969]

my pond is 1200 gals...my U.V is 9 watts ( i no longer use it as of this year, i broke the quartz sleeve)..my pump is a tetrapond 1200 gph. i ran the full 1200 gph thru my U.V and it performed flawlessly. my filter is a 70 gal DYI stocktank filter. i run an extra 1000gph pump "venturied" into the top of the filter for more aeration and circulation...you should be able to do the same but off one pump.