Introduction: Building a Large Trickle Filter for My Turtle Tub.

After checking the levels of ammonia, nitrates and nitrites in my turtle tub i discovered that all my old filter was doing was making the water look nice. There just wasn't enough capacity for Bio media, and what little there was wasn't being effective used. So, I started searching around the net for a better system, what i settled on was a trickle filter. This one specifically is inspired by Jim's "Crazy" Bio-Filter over at SO props to him for coming up with an awesome filter design.

Basically the theory behind trickle filters is that the bacteria that break down nitrates and ammonia like oxygen. It seems most filters rely on the water being oxygenated enough to keep the bacteria happy and hungry. Trickle filters step this up a notch by allowing water to trickle through a chamber filled with bio media ensuring plenty of contact with oxygen for the bacterial colonies without letting them dry out. Apparently they are super efficient, and that's good for turtles because turtles are messy little armour plated monsters.

Step 1: Supplies

For my filter i used...

-1 4' length of 4" ABS pipe-------------------$25
-1 short piece of 3/4" PVC pipe------------scavenged
-1 3/4" PVC pipe cap -------------------------scavenged
-1 3/4" slip to threaded adapter------------>$2?
-1 3/4"threaded to barbed adapter-------->$2?
-approx. 6' of 3.4" non-kinking tubing-----scavenged
-1 pump-------------------------------------------$80
-2 salad dressing shakers------------------$2 each
-64 plastic dish scrubbers-------------------$1.50 for a pack of 8
-1 package "NU-Foam"-----------------------$4.50
-550 paracord-----------------------------------$ $6 for 50'


A drill with 3/16 and 1" bits
a hacksaw
a blowtorch
a nail

Step 2: Building the Body of the Filter

I started off with the body of my filter.
First thing i needed was a place for water to come in, so i drilled a 1' hole about 2' down from the top of my abs tube.
Next I needed a place to let the water out, so i drilled 4 more 1' holes around the base of the tube. Following that i switched to the 3/16" bit and drilled a ring of holes around the base about 4" up. I threaded the paracord Through these holes to act as a barrier to keep the scrubbers from falling out the bottom.

Pretty simple so far eh?

Now were going to cram it full of as many Scrubbies as possible.

Although My pictures show me adding a disc of nu-foam to the top, it IS NOT NECESSARY and is just begging to air lock causing your pump to pump 400 gallons per hour onto your bedroom floor. I recommended skipping that experience.

Step 3: The Spray Bar

The spray bar Is the part of the filter that actually hooks up to the pump. To build mine i started by taking about 8" of 3/4" PVC and drilling a bunch of small holes along the end 3 inches or so reaching half way around the pipe. Next I took a pipe cap and cut to down to about half its length and drilled a hole in the end of it.
Assembly is simply a matter of sliding the pipe through the inlet hole, and putting on the cap and adapters. You don't need to worry about gluing the parts together or anything. For the sake of aesthetics i cut the length of the spray bar down as short as i could get it.

Step 4: The Pre Filters

That's right, I'm making a filter for my filter.
The trickle filter I built should be good for keeping my water chemically clean, but doesn't do much to keep it looking clean and clear. That is where the pre filter comes in. I opted to build a small one that mounts on the intake of the pump, that way it also serves the purpose of keeping my turtles from getting their heads stuck in the pump, and screens out all the solid waste and debris in the water, hopefully increasing the lifetime of my pump.

I built 2 pre filters so that i can swap them out for cleaning and let them completely dry and dechlorinate before putting them back in. chlorine+bacteria=dead bacteria. not what i want while trying to establish a biological filter.

Apparently i didn't take any pictures of the build itself, fortunately, it's really simple, so pics of it broken down for cleaning should be just as good.

To start with I fired up my blowtorch and heated up a nail. Then i used the hot nail to melt a grate into the bottom of my salad shakers. Next I used a an exacto knife to cut out a hole in the lid cap that i could friction fit over the pumps intake. I only cut up the cap on one of the lids, it stays on the pumps intake and whichever pre filter i'm using gets slipped into it.
Ta-da, now the body of the pre-filter is done.

I used 2 scrubbies right at the grate to act as coarse filter pads, then filled the rest of the chamber with discs of NU-Foam to act as medium/fine filter pads.

Step 5: Observations Afterwords.

I've had this filter up and running for a few weeks at this point. So far It's required minimal tweaking and seems to be working perfectly.

About 6 hours in i discovered that having a layer of foam at the top of the filter below the spray bar was a bad idea. It slowly got an air pocket trapped under it causing water to build up and start overflowing the top of the filter. not good. Fortunately i caught it just in time and only had to clean up a medium sized puddle. even better, it didn't get to anywhere where it could get through the floor. i didn't want to have to explain to my new neighbors why there was water running out of their plug sockets and light fixtures.

I also added a few more scrubbies in to the filter to fill it up a few more inches. this was mostly to make it quieter since i sleep about 3 feet away from it.

The pre-filter works amazingly. It does however need to be cleaned once a week. that takes about 5 minutes in the sink, so it's no big deal.

lastly, my only problem with this filter is that it causes no surface agitation. that does make it incredibly quiet, however, it also lets a nasty ass protein film form on the surface.
All i need to solve this problem is a better (or second) power head as the one i have right now is to small to agitate enough of the surface.