DIY internal cannister/air filter

[couchy]

I got a bit creative today and thought i'd share it.

I needed a cannister filter for my new 700ltr grow tubs,

To save money i thought i'd make a large air driven filter out of a 20ltr bucket.

So this is really just a home made air box filter on a large scale.

Here are the things you'll need;

a 20 ltr bucket with lid.(handle removed to avoid rust)

a length of PVC (i used 25mm but bigger would have been better)

A 90 deg elbow to suit pipe size

some air line hose

a round air stone to fit down the PVC pipe

Some egg crate (i use a bread tray)

something to prop up the egg crate ( i use corrugated plastic sheets)

Some media ( i use some shells and coral)

coarse filter sponge (purchased from Lionel)

filter wool (wadding from spotlight)

Tools; a good stanley blade, hacksaw, drill, jigsaw, scissors

and beverages

Start by adding your 'stands' for the egg crate.

I have used some corrugated plastic in an X shape but pieces of pipe cut to same lengths will do.

corrugated plastic

and in place with media added

cut a circle piece of egg crate using a jigsaw

Here is the platform in place above the stand and media

note; leave a hole for the pipe in the egg crate

Next i add the coarse filter matting (courtesy of Lionel - Zigzagfish)

Cut to fit

then add filter wool, i buy this from Spotlight as "wadding" much cheaper than LFS

then i repeated the last 2 steps, 1 more layer of coarse matting topped off with a final thick layer of wadding.

Next you will need to cut and fit your return pipe.

then you need to drill the top of the elbow and feed the air line through. This must be a tight fit.

Attach the air stone and pull the air line back through the elbow so the air stone is totally within the pipe.

in picture 1 of all equipment used, note the PVC is cut in half vertically. this is so water is pumped from this height from the bottom. this means waste can collect in the bottom of the media without being sucked back out through the return pipe.

Cut a snug hole in the lid to fit the PVC through

Lastly drill holes in the bucket lid for water inlet, obviously this must be under your water level and the return pipe just above.

You will need to dismantle the whole thing and rebuild around the return pipe.

Here's the finished product.

Hope this was interesting or helpful to someone>

Cheers Couchy

[moosedagoose]

pretty cool mate well done

[Ged]

Great DIY.

I could understand the instructions and photos but I think you missed out which step the beverages should be utilised. I took it as a given that it was before Step 1 and as a result don't have anything to show for a hard day in the shed.

[dogboy]

looks good, i agree about the beverage comment, no DIY is complete without it.

also i would have added another PVC pipe or two and lose the airstones for max water flow, with 20L of media you will want a lot more water going through it to reap the rewards...and 25mm will be great ,if you go too wide and you may not get the lift from the air that you want.

great idea ,thanks for sharing

[couchy]

Sorry beverages were after each step...

You might be right about a second or third return pipe.

I have to make another one so i'll give this one a go then adjust for the next.

Cheers Couchy

[joller]

nice work, i'm gonna do something similar in a diy sump, gravity fed though

[Kartoon]

Nice one. Im hoping to do something similar in my grow out tubs. Great idea

[couchy]

Turned it on today, works great but flow rate isn't enough to make the most of the 20 ltrs of media.

Dogboy was right 2 return pipes would be better.

Will be making another this week then adjusting this one to have 2 returns also.

The 25mm pipe is a good size after all but definitely need 2.

Cheers Guys.

[fishdance]

I use powerheads instead of air lifts. Just stick some pvc pipe or silicon tube on the output of the powerhead before burying it. No lids, no sponge, no egg crate required but use 6mm gravel - large enough not to get sucked into the powerhead. A 1000LPH powerhead is only about $10 so I often have 2 bucket filters in one tank to alternate cleaning and for backup/peace of mind. I only clean when the water flow starts to slow down.

[fishdance]

DIY air driven filters are excellent if the water depth isn't too deep since the water depth affects air volume/filter output. I have seen a lot of people use gravel filled plastic flowerpots (line bottom with plastic fly screen) or a sponge block with PVC pipe speared into it.

On a 700 litre growout tub driven by airlift, I would consider making a fluid sand filter out of your 20L bucket instead since this doesn't need as much water turnover although this would be only biological filtration.

[zigzagfish]

Well Done Ben

You will have to show us at the next DIY night at the club

Cheers

Lionel

[couchy]

Fishdance, I thought about doing that with a powerhead which would give the water flow but am using air from a constant loop in the room so no extra electricity usage in the room.

I will be running 2 of these in each tub. Also i will use the water in the tubs to do water changes or top ups to the rest of the room. The water will be getting changed completely (in volume) every fortnight. I'll be doing constant water changes in and from the tub which will assist in fry growth so water quality should stay at high quality.

Its working well but i'm looking forward to making the next, new and improved model.

Cheers Couchy

[fishdance]

Fishdance, I thought about doing that with a powerhead which would give the water flow but am using air from a constant loop in the room so no extra electricity usage in the room.

I will be running 2 of these in each tub. Also i will use the water in the tubs to do water changes or top ups to the rest of the room. The water will be getting changed completely (in volume) every fortnight. I'll be doing constant water changes in and from the tub which will assist in fry growth so water quality should stay at high quality.

Its working well but i'm looking forward to making the next, new and improved model.

Cheers Couchy

The powerheads only draw 10 watts each although you can get bigger/stronger too.

I run some 500L tubs and if you want to utilise air then I would recommend a fluidised bed filter. I have attached a couple of pics but don't want to detract from your thread so I won't go into too much detail

A row of tubs - self cleaning and auto water change

Blue barrel (above) at end of row is the bio-filter. It is driven by air to fluidise the media (pictured below)

I use low density polyethylene pellets as bio media. These are approx 3mm granules with specific gravity 0.95 so slightly bouyant and very easy to fluidise.

[couchy]

Fishdance,

Don't worry about detracting from my thread, please start your own or add more detail.

Keen to see more of your setup.

Show more of the auto cleaning and auto water changing.

Obviously i only have 1 tub at the moment and 1 more to go in. So yours is on a much bigger scale than mine but keen to see how it all works.

Are the tubs used for growout or breeding etc.?

Cheers Couchy

[couchy]

Also is the HDPE used in place of sand in a fluidised filter or does it also absorb bacteria?

Unsure of its purpose or how your filtration works.

I use sumps and air driven DIY box filters. Have no knowledge or experience with these.

Cheers Couchy

[Link2Hell]

Couchy

Winston uses the HDPE as the medium instead of sand as it fluidises (mixes) easier

due to the weight of the particles

plastics are very good base media for bacteria

[fishdance]

Fishdance,

Show more of the auto cleaning and auto water changing.

Cheers Couchy

The tubs are slightly conical cylinders and work on a vortex / swirl filter principle with a central standpipe. This standpipe determines the water level within each tub/tank so its easy to change water levels when required. - As growout tubs, I sometimes lower water levels to concentrate food initially. - I add water tangentially and off center (see photo below) to create a slow but steady swirl of water within each tub which collects any detritus (large or fine) into the very center bottom of the tank. There is a slightly wider pipe that fits over the central standpipe that is 2cm higher/longer than the standpipe so water (and detritus) is carried off the bottom up between these pipes and out. I deliberately made the space between these pipes narrow to exclude fish and I made sure the outer pipe is still below the top of the tank in case there is a blockage. If one tub gets a large buildup of sludge on the bottom, I turn up the water flow for an hour which "swirls" it totally clean. The water carries the sludge to the mechanical filter stage. Its important to remove sludge out of the water column as soon as possible to reduce the workload on filters.

I also have an auto fish feeder that dumps small sized pellets into the sump directly into the water pump intake which carries food pellets to all the tanks with the incoming water. I can feed as much and as often as I need this way. My pump can handle up to 6mm sized soft particles so I make sure my pellets are well under this. I also add some live artemia automatically in a similar fashion. Soon? I will be growing green water in IBCs (1000L) outside in staggered cultures as I know green water is very nutritious and add great colour to fish. Its hard to beat real outdoor pond grown fish for colour but I hope to come close by feeding live green water.

There is also an auto water change by adding in fresh water slowly 24/7 that displaces old water out down an overflow drain. I've added some fancy self cleaning sieves and siphons to this arrangement but will keep this topic simple for now.

The resulting filter system is a ridiculously simple design which I like, especially because its so simple. A 200L barrel of water and these fluidised granules acts as the biological filter. I also have a mechanical filter which is another container of same media but this is kept static with the water gravity draining through to mechanically filter. Here the water simply drains and trickles through the media leaving dirt trapped behind. To clean the mechanical filter I allow the barrel chamber to half fill whic floats the media, swirl the media manually to dislodge trapped dirt and then open a bottom drain to empty dirty water waste. Confusingly, I use the same media for totally different purposes. Also confusing is there are several similar looking filters such as floating bead filters, K1 (biofilm) filters and pressurised sand filters - all with own pros and cons - but with different designs and purposes. Mine is essentially a fluidised sand filter but using floating media. This filter solution is what works best for me but obviously there are a lot of other options and each fishroom has different considerations.

Since the biological filtration is so effective, the water coming out is low in oxygen so I re-oxygente it by passing it through a degassing column before returning it to the fish. This is also quite simple. Its a vertical tube whose open ended bottom is under water. I add air to the bottom which has to rise to get out because the bottom is under water. Water trickles down this tube over bio-balls which helps to remove co2 and gain oxygen. I deliberately use a counter current situation which is much more efficient than if water and air were both moving in the same direction (concurrent).

A power failure would be catastrophic for highly stocked tanks so I have backup power on automatic switch over capable of 12 hours protecting my air pumps and also a standby petrol generator I have to manually switch over. The water pump is on a separate electric circuit to my air pump and there is an air driven sponge filter in each tub as well for extra cheap insurance.

[couchy]

Excellent set-up and detail,

Cheers for the update.