My home made bilogical filter

[gelf]

Hey all,
Those that know me would know I'm a mad man for cultivating and feeding live foods to my Blue-eyes and Rainbows.
Also, these fish have tiny fry.

The problem: Commercial filters all rely on a combination of biological, chemical, and physical filtration. The pysical filter was my problem, be it a sponge, gravel, or some other form of porous medium. This physical filter removes anything solid that passes through the filter, be it food particles, live foods, or even eggs and fry.
The solution: Develop a filter that had no physical filter component, where the water could gently flow over a large surface area without passing through a sponge or other filter medium.

My initial idea came from a presentation at an ANGFA NSW meeting by Leo of a biological filter developed by an ANGFA Qld member. I took this idea and had a play till I cam up with what I consider a better filter that is effective and simple to make.

My filter:
What you'll need:
* Rectangular PVC downpipe (choose diameter per filtration need)
* Enough straws to pack in each end (I like the tough McD straws)
* 20mm diameter round PVC riser
* ¾” Grommet
* Ice cream container lid, or similar
* 4x 290mm long zip ties
* An air supply to run the filter

Using 105x55mm rectangular downpipe packed with 230 McD straws this filter has an effective filter area of ~150,000mm2

Construction:
Choose downpipe diameter to match your filtration need
You’ll need 46cm of rectangular PVC downpipe.
Drill a 25mm diameter in the centre of the downpipe as shown in the attachments
I find 105x55mm rectangular downpipe more than adequate for 2’ tanks
Choose a straw no longer than 210mm, and preferably with tough sides to prevent collapse
I find the McD straws are a good length, and are tough
You will need quite a few, so buy a bulk lot or ask nicely. Do not steal
With 105x55mm downpipe I need 230 McD straws per filter
Pack the straws into each end of the downpipe
Pack slowly and jiggle as you pack to ensure the straws pack properly. You will need to force straws in to ensure the entire lot is packed tight
Push the straws flush and use something through the drilled hole to push any straws back that have come in too far
Cut your 20mm diameter round PVC 10mm longer than the desired water depth of your tank. This is your riser
Using an angle grinder, grind 3 wide grooves at the base of the riser
Insert the grommet and then push the riser into position
The filter when active will tend to float. It will need a base with a weight.
I use an ice cream container lid held in place with zip ties. I then use a potted aquatic plant to hold the filter down
The amount of air blowing through the air stone will determine the quantity of water that passes through the filter per hour. Choose a slow flow rate to maximise biological filtration. Choose a fast flow rate with the assistance of an air curtain to assist in maintaining suspended food particles
I use a length of solid air tube with an air stone on one end, and an air flow tap heat-glued on the other
This is just slotted down the riser and connected to an air line.

And there ya go,
You have a biological filter that won't remove food particles, kill fry, or damage micro-fauna.

Cheers
Tony

[gelf]

And all up and running:

[ILLUSN]

Nice work Tony, bout time you posted up pics of your filters, like i said before VERY IMPRESIVE!!!!!! well done

[gelf]

Mate, always refining and testing. Had to be happy I'd refined to a level that there was no more refinin' to do before I was ready to sprout my wares.
I'll have to do a full step by step article and put it up on my site.

[scott bowler]

thats a great idea well done thank you for shareing . i like it keep it updated on how it goes .

[gelf]

Hey Scott,
I've been using these for over 6 months now. Or at least some version of the above
Lots of refining to get the construction simple, cost low, maintenance and cleaning minimal and easy, and effectiveness great.

Here's an update for today: I made 3 filters from scratch today, totally cleaned out 2 tanks, potted up 8 aquatics, and did the lot in under 4 hrs. Those filters are just so easy

[ILLUSN]

Hi tony, I'm being lazy and copying your design for the breeding tanks in my new fish room, just wondering how long does it take for the filter to be "fully" colonised, how often do you clean the filter (with no mech filtration is it self cleaning?)

[OscarManAlpha]

I'm going to buy shares in the company that produces Mcdonalds straws..

Look's like production will rise when the idea of these filters kicks off.

[gelf]

just wondering how long does it take for the filter to be "fully" colonised, how often do you clean the filter (with no mech filtration is it self cleaning?)

Hey mate,
Can't answer your first question, that's 1 for a water biologist. I let them settle in for 2 weeks, the same amount of time i let any filter settle in before adding fish.
As far of the cleaning goes, it's just a matter of cleaning when the sediment builds up too much, and that time will depend on what you're feeding, how many plants, etc. The other cleaning is if algae builds up in the straws of the riser. Aside from that, it's simply a matter of set and forget.
I've done a full article as promised. Look up 'DIY Biological Filter' on http://www.gelf.com.au/fish/index.html to download the pdf file.
Cheers
Tony