If you want to save some money on replacement filters for the $10-15 "5/15" Aquatech brand aquarium filter, here is how.
There are two methods I will discuss here (using part of a factory filter, to hold the "activated carbon" charcoal substance, and skipping it entirely by just cutting a piece of material to fit the filter machine. There are two filters you can replace, but one is a "bio filter" and shouldn't be replaced unless there is some problem with it. Mine got full of some kind of pink algae or mold and got tossed out. Instead of buying a new filter machine just to get the bio-filter, I tried making one, to make due until I could go to the store. It works well, for aquarium use, and would work excellent for a non-freezing chicken water bucket, a lizard or crab aquarium/habitat, or a bait-bucket.
Step 1: Buying Your Filter Material and Cutting It
This is super simple. Go to HD hardware store, and ask the clerk for this product. ***Make sure you get the kind made for scouring dishes, not sanding paint or for carpentry work. The ones for dish scrubbing are simply plastic fibers and do not contain toxic agents or powders. They come in packs of 6 for around $1 to $2. The factory filters are $3 each, or somewhat cheaper in bulk packs, but may incur shipping costs. The ones I make can be rinsed in a garden sprayer and re-used at least once, maybe many times, depending on your application, your tank or water conditions and maintenance, and your "bio load" (how many fish are in there eating and pooping).
Take the green scouring pad, press it against the factory filter (you get at least one with the filter machine), size it, nick or mark it, and cut to fit. (worry about the width, not height. I will explain this in a minute).
(If you are replacing the "bio filter", see the next step for that.)
If the filter replacement is too wide, it will "bow" and not seal well, but may work. If it is too narrow, it will not seal and may become dislodged, and won't filter well.
Note: I originally posted this with the filter sideways. hahha. I found out I was using them wrong. There is a notch that matches up to the inlet water tube, and a small cutaway on the top of the filter there, which prevents flooding if the filter is full. The green scrubbies work fine, especially if cut properly, or sometimes not even needing cutting if they are a little shorter than the factory filter. Just keep an eye on them for when they're full of debris.
The green scrubbie is shorter than the factory filter, which is already designed not to cause a spill if water goes over the top if the filter is clogged. You can replicate this function without making the bypass notches, but I prefer them for higher flow, and the action the water crossing the filter media has in trapping particles.
Step 2: Fitting the Filter, Making Replacement Bio-filter If Necessary
If your original bio-filter (designed to trap some healthy aquarium bacteria and/or plant life and "seed" the water, to prevent toxic conditions for the fish) is damaged, lost, or contaminated, you can thoroughly clean the machine and replace the bio-filter with this material.
The green scrubbie will be too narrow to stay put in the plastic holder. You can cut two pieces to fit (trial and error, nip off a little until it fits snugly. I left a gap in the center of mine, to facilitate speedy water flow. The water will mostly go through the bio-filter, but increased flow keeps the waterfall at the end steady and making a soothing sound.
To copy the factory filter and re-use the plastic plate, with new charcoal, just pull off the original blue media with pliers. Scrape the surface where it was adhered, with a hobby knife, or file, or rubbing on a sidewalk to grind it off. It doesn't have to be perfect. Cut (carefully, with good scissors or a hobby knife, against a safe cutting surface) the new green material to trace the template of the plastic backing piece (including matching the notches for the water flow on the sides). Use a hot glue-gun to adhere the new piece along the sides and. bottom. No need to glue the top of the green filter. It's short.
(Glue gun photo came from Amazon
$7.50 and free shipping
Step 3: Maintaining and Replacing Your Filters
You can simply rinse the filters as necessary to prevent obstruction or smelly contamination (full filter). If the filter is really clogged or not easily cleaned, just discard it in the trash.
If you make many duplicates from the cheap scrubbie pads, you should be set for a long time, and prepared to replace the filter quickly if necessary.
If you are using the one glued to the factory filter plastic plate, you should be able to dump out the charcoal and power-rinse it, add more charcoal and move it with your fingers to fit the filter back into the filter machine. I recommend replacing the charcoal whenever you remove or clean the filter.
You can tear off the scrubbie pad material and scrape the glue off the plastic plate, and dry it, before repeating the construction process to make new ones. The filter plate should last through at least half a dozen filter replacements. Friends with a similar machine may be asked to save their filters for you to re-cycle (the plastic plates).
Good luck, and thanks, Instructables.
(Sprayer photo came from an air-conditioning repair site