Biofilter Design

[urglik]

howdy,

i've decided on a design for a filter and wanted to know if anyone thought there might be any issues.

i'm going to use an open cell foam for the pre-filter and the biofilter.

with the design below, the water flows in the top center onto a plastic mesh strainer upside down

on the foam to spread the water around. the water flows through two 1 inch layers of foam sitting on a plastic

egg crate grate for support. the water then drains on to a stack of 1 inch foam layers separated by egg crate.

i think i will use 6 layers of foam. the biofilter sits above the drainage tube.

thank you.

 

[morewater]

IMO, an up- flow filter would be much more effective.

The "dirt" then settles on the bottom of the tank, rather than clogging up the filter media.

 

[Nepen]

agree with morewater.

Also, the biofilter media that you are using (the foam) overtime will get clogged and need replace even with the 2 layers of pre-filter on top. I suggest use something easy to rinse like lava rocks.

Up flow is better IMO, but there is this shower filter that water raining down on the filter media that people use for koi pond (I think it called Bakki shower filter) that's similar to your idea.

 

[Mmathis]

@Nepen [and I might be wrong, but] I'm not sure the OP is talking about a shower filter as those have to have the media open to air.

@morewater My Skippy is an up-flow. I can attest to the fact that, despite use of filter pads, the crud does flow up with the water and back out into the water column! In order to keep the crud from rising, I have to dial back on the water flow which makes for a more gentle flow.

With a down-flow filter, it's supposed to be easier to change/clean the mechanical filters since they are on top and are easier to access. The only way I can "clean" the mechanical filters in the Skippy [up-flow] is by either pulling everything and rinsing it, or by pouring massive amts of pond water over the media to force the accumulated crud down to the bottom where I can flush it out via the bottom drain. Both are major PITA's! I am thinking of switching to a down-flow type.

On my QT, I have a trickle tower system [similar to a shower] [very DIY!], but you still have to have good mechanical filtration BEFORE the water gets to the TT. I have my small pumps in plastic pump-filter boxes. I also keep a couple layers of quilt batting under the spray-bar for the TT -- even with the filter boxes, there is an amazing amt of crud that collects in the quilt batting, and the idea is to keep the bio-media as clear of debris as possible.

@urglik Why don't you do a quick search here on down-flow filters -- I seem to recall a sticky somewhere, maybe in the DIY or "Equipment" sections. I like your plan, personally. Just be aware that you'll have to be cleaning filters often to avoid an over-flow. And, as every pond is different, likewise, every filter will be different. Sometimes you won't know how something is going to work until you actually start using it. "Things" are always going to pop up -- things that you weren't expecting to happen......no matter how well you planned......

 

[Nepen]

@Mmathis Yes the Trickle tower is the one more like his design, i just couldn't remember the name. But the shower is also similar

My problem with the down-flow is the over-flow. We usually take vacation 2-3 weeks at a time and no one to come take care of the filter. My old pond i have the down-flow and the water over flow very often and I have to be pro-active in cleaning the filter. I lost most of the water due to over flow 2-3 times I dont remember exactly with my old pond. Now with the bog, and up-flow, I have no problem at all with over flow. I got lots of muck flowing back to the pond since I think the pea gravel is not doing a good job trapping the muck as the quilt batting, but I rather have muck (that I can clean later) than worry all the time (especially during vacation) about over flow.

 

[Meyer Jordan]

For truly efficient filtration, mechanical and biological filtration should be housed in separate units.

 

[Mmathis]

For truly efficient filtration, mechanical and biological filtration should be housed in separate units.

Agreed!

 

[urglik]

For truly efficient filtration, mechanical and biological filtration should be housed in separate units.

could you please elaborate

 

[urglik]

wow. thank you for all the replies.

i think it would be a good idea to make my overflow hose the same size as the input to be safe. thanks nepen.

i opted for the down flow approach to use wet/dry biological filtration. not that i have a learned opinion on it. just like it.

regarding the sediment concern, i have a 100 foot watercourse with the pond which filters the pond of sediment and biologicals.

i had planned on using the filter as an adjunct during the warmer months and during the transition periods in spring and fall when the course isn't running.

during spring and fall there would be some pond sediment, but i will be on it daily.

i'm committed to this design now due to available materials, time, and resources.

i look forward to building my next filter.

 

[Meyer Jordan]

could you please elaborate

Pretty much self-explanatory.
Suspended solids should never be allowed to accumulate to any noticeable level in a biofilter even for a short period of time.
The availability of Oxygen to the nitrifying biofilm will be restricted. Sediment accumulation will create 'channeling' of the water flow negatively affecting the bioconversion efficiency. Frequent cleaning may mediate this issue, but frequent cleaning of a biofilter is not usually the best course of action.

 

[Usman]

howdy,

i've decided on a design for a filter and wanted to know if anyone thought there might be any issues.

i'm going to use an open cell foam for the pre-filter and the biofilter.

with the design below, the water flows in the top center onto a plastic mesh strainer upside down

on the foam to spread the water around. the water flows through two 1 inch layers of foam sitting on a plastic

egg crate grate for support. the water then drains on to a stack of 1 inch foam layers separated by egg crate.

i think i will use 6 layers of foam. the biofilter sits above the drainage tube.

thank you.

I agree with others , if u make the inlet from below and outlet from above it will need less maintainence , or if u have low pressure pump and your ready to clean foam every few weeks , this will work too .

 

[Meyer Jordan]

wow. thank you for all the replies.

i think it would be a good idea to make my overflow hose the same size as the input to be safe. thanks nepen.

i opted for the down flow approach to use wet/dry biological filtration. not that i have a learned opinion on it. just like it.

regarding the sediment concern, i have a 100 foot watercourse with the pond which filters the pond of sediment and biologicals.

i had planned on using the filter as an adjunct during the warmer months and during the transition periods in spring and fall when the course isn't running.

during spring and fall there would be some pond sediment, but i will be on it daily.

i'm committed to this design now due to available materials, time, and resources.

i look forward to building my next filter.

If you are indeed going to stick with this design, the overflow outlet should be at least twice as large as the inflow.

 

[urglik]

If you are indeed going to stick with this design, the overflow outlet should be at least twice as large as the inflow.

i knew someone would say this. i wanted to avoid it just because i had to put two outflow outlets because of ribs on the container i'm using to achieve 2x. i would have to do two overflow outlets to accomplish the 2x in over flow. good advice though.

 

[urglik]

Pretty much self-explanatory.
Suspended solids should never be allowed to accumulate to any noticeable level in a biofilter even for a short period of time.
The availability of Oxygen to the nitrifying biofilm will be restricted. Sediment accumulation will create 'channeling' of the water flow negatively affecting the bioconversion efficiency. Frequent cleaning may mediate this issue, but frequent cleaning of a biofilter is not usually the best course of action.

makes sense to me.
with one or more containers, the pre-filter must be doing it's job.
it would seem then that with only 1 container in a filter system, to avoid suspended solids accumulating in the biofilter,
a top to bottom approach with the biofilter being washed with water continuously and not submerged
could lead to a cleaner biofilter then the bottom to top approach.

 

[Meyer Jordan]

makes sense to me.
with one or more containers, the pre-filter must be doing it's job.
it would seem then that with only 1 container in a filter system, to avoid suspended solids accumulating in the biofilter,
a top to bottom approach with the biofilter being washed with water continuously and not submerged
could lead to a cleaner biofilter then the bottom to top approach.

It won't.