Before you run out and buy one of those premade drop in pond filters, take a look at this easy to make drop in filter. It will do the same job as any drop in that is being sold and for a fraction of the cost. It will probably be even better since it will have more area for bio material. Not only that, you'll never be trapped into buying their replacement filter pads. I have used these for years and once seasoned they do a very good job, although they are a bit of a pain to clean, but so are the store models. If you are looking for a small sponge filter for your fry tank, look in "Raising your Spawn" http://www.tadege.com/raisingyourspawn.htm for instructions on a very easy cheap diy sponge filter.
Be aware that this type of pond filter is not intended for a large koi pond, no matter what the store model says. They work very good for small ponds with small to medium fish load. If your pond is over 1000 gallons with a lot of big koi, this pond filter will not do the job for you. I use this type of up flow filter for my large koi pond, but they are modified external filters in 45 gallon barrels with forced air cleaning, with pre-filters and settleing chambers, also. A large drop in is not practical due to the fact that you have to remove them to clean. You could use multiple filters like this but it would really add to the work load for you when cleaning each month. If you need a larger pond filter for a heavy fish load in a large pond look at, http://www.tadege.com/wakinfilter.htm
Easy Build DIY, Do It Yourself And Save.
For this drop in filter you will need a filter container with a lid. I just use a 5 gallon pail. Rather than mess around finding used and cleaning it I just buy new, under $10 (Home Depot) with the lid, buy the white lid, much easier to put on and take off. If you have a good clean 5 gallon pail you can get the lids at Home Depot by themselves, these new lids snap on and off a lot easier than the original. Keep in mind that your filter will need to be completely under the water surface, so if the water depth is less than the height of a 5 gallon pail you will need to use something else for the filter container. Rubber Maid makes a number of strong containers that have good lids and would work good. You will also need some type of grid material, I have used the guard from an old box fan, but use what you have. I'll get into bio and filter media later.
If you don't have a submersible pond pump you'll want to get one that will turn over your pond water volume at least once an hour. If you have time, you can probably get the best deal on Ebay, other wise Lowe's and Home Depot always have a large selection, these last for years and use very little electric. You will also need a stiff plastic pipe or hose to raise the water from your filter to over the top of the water level if you want to hear the sound of running water, this also helps to keep the air up in your pond. Look in the plumbing department for something that will fit your pump outlet. Most are 3/8" or 1/2" but check your pump to be sure, use the largest you can. It would be nice to get everything in one trip to the store, but has never happened for me. Try to have a helper for parts and beer runs.
The only tools needed will be a drill and bit. Use a 1/4" to 3/8" bit. The size is not to important but small holes will clog up faster and if they are to large your small fish will be sucked in, they hate that.. In the bottom 3" of your container drill holes every 1/2" or so for 3 inches up from the bottom all the way around. If you have a lot of leafs that falls into your pond you may want to make these intake holes 1/2" if your fish are large enough not to get pulled into the filter. On this filter I used a soldering iron and just melted in the holes. This picture is a 5 gallon filter that has been in use for years that I am using in my spawning tank now. The plastic will get brittle in a couple years, but it's easy to replace, no parts list, just get a new pail.
It's not important to have these holes evenly spaced or anything, this is just the water inlet.
You will need a grid of some type that will fit into your filter box or 5 gallon pail about 6" down from the top. I made mine from a old box fan guard, but it doesn't really matter what it is as long as water can pass through it easily and will hold down the filter mat. Plastic is best, won't rust or cause other problems. If you cut up the laundry basket, make sure you get a new one before it's discovered missing!
Your bio material can be any number of things. For years I used lava rock, the kind used in gas grills. Buy this in the garden department as yard landscaping rock and it will be cheaper than for grills, maybe $4 for more than you will need, always start with new. Do not use old lava rock from a grill or any other thing that has been contaminated in any way. Avoid used landscaping rock that may of been sprayed with anything. Even with new you will want to rinse it very good, or your water will turn red. I have switched over to bio balls lately. They are much lighter (so light that you'll have to put a brick in the bottom of your filter or it will float) and easier to clean. I have them in my Koi food section for $20 per 100, it will take 2 packages of these for a 5 gallon filter and they will last you forever. You could also use cut up PVC pipe, hair curlers or any such thing as long as it has a lot of surface so bio can live and grow on it. Give it some thought and you might come up with something even better. I've seen filters filled with plastic forks, even plastic shot gun shell wads. All you really need is something with a lot of surface for the bio to grow on. This is an add on to this page and I just saw it a couple days ago, the filter was filled with the plastic 6 pack loops that soda and beer come with and was working very good, I would guess that a bar could give you a instant supply, or you could always have a party, don't forget to invite me . Avoid things like brushes that will be hard to clean. Keep in mind that you will have to lift this filter out of your pond or tank to clean it, so try and keep it as light as possible. If you stop using a filter for a long time and let it dry out, be sure to really scrub the bio material before using it again, you may just want to replace lava rock if that is what you're using. The bio will of dried up and possibly be growing mold or something else you don't want in your pond water.
Fill your container to about 6" from the top a with the bio material you have chosen, a little less if you are using floating bio balls. On top of this you will need some type of filtering material to remove the fine particles from the water, it will also have some bio action. There are any number of mats and things that are sold at the pond supply stores you can use. I have seen a/c filters cut to size, regular filter pads cut to size, and sponge material cut to size. All in all I have found that just regular quilt batting works as good as anything, and here is the real plus, it's cheap enough to just change with new when doing a cleaning. You can go to a fabric store and buy a large bundle for a couple dollars, I simply go to K-Mart and buy the largest, cheapest pillow that has synthetic filling (all cheap pillows do), $3 or $4 and use the filler. Just rip the end of the pillow open and use as needed. I use 2" or so above the lava rock and when I clean the filter I just replace it. You can wash it out and reuse it, but you'll get real tired of this real fast, it's not nice to deal with after a month in the pond. A washing machine ties it in knots, been there done that. One other thing, if you use the batting from a pillow, save the pillow case, in most cases it will also be polyester and you can slip this over the entire filter and use it in a hatch tank so the small fry don't get sucked into the filter, they will last a long time.
Now just place the grid you have right on top of the filtering material. Set the pump on top of the grid to make sure there is enough room to get the lid on, if not just remove some of the lava rock or bio balls so that you have room for the lid. Position the pump so that the oulet is near the center of the container, and cut a hole in the lid so the outlet pipe from the pump can pass through it. When you cut the hole you can just use whatever drill bit you have in the drill and ream it out so the pipe will fit. You can pass the electric cord from the pump right though the hole along with the outlet pipe. This hole doesn't need to be water tight, but you don't want it so loose that the water isn't drawn up from the bottom of the filter. The pump will always stay with the lid, so if you make it tight that's a plus. On the first pump picture I have a hose, but you can get lawn sprinkler risers in the plumbing department that will slip right over the pump outlet and cut it to length so that it will be about 6" to 8" above the water when the filter is in the pond, like a mini waterfall, it will help to keep the aeration up in the pond. If the flow is to much and shoots the water into the air to far you can just slip a larger piece of PVC pipe over it to slow the flow without effecting the volume of water. Also sprinkler risers are threaded and you can put on a cheap lawn sprinkler head for a fountain spray. If you want to run the water in a water fall or spitter, use a hose to the location you want. Long hoses really effect the amount of water your pump will put out, use the largest hose you can. Use a larger pump for a long run. Raising your outlet level to a water fall will greatly effect the out put of water also, this is called head pressure. All pumps are effected, but smaller pumps really drop a lot even with a little increase in height. You can usually find this information on the pump box, so be sure to check. It's always better to have a larger pump than is needed, you can always slow the flow down if needed, all but the smallest pumps I have seen have a built in volume valve, this is not a place to try and save a few dollars. You want your pond water volume to turn over at least once an hour, more is better. I don't give electrical advice, but use a little common sense, always a 3 prong plug and you can buy extension cords with built in ground fault interrupters. Water and electric don't mix well, so always turn off the power supply when cleaning or repairing.
Here is this filter in operation, I am running a 350 gph pump and the 3/8" riser from the pump wanted to squirt the water some 6 feet into the air, so I slipped a 1" scrap piece of PVC pipe over it to calm it down, it still put out a real gush even with the 1" pipe. (the dark on the pipe is active bio action, you want to see this inside your filter, don't scrub it off where it can't be seen, it's the good stuff.)This filter is in use in my spawning tank, about 300 gallons, but I have used these on ponds up to 1000 gallons with a larger pump, with very good result. You will need a pump big enough to turn the water volume over at least once an hour.
Filter cleaning will depend on the fish load, but usually once a month is enough in mine. Lava rock will clog much faster than bio balls and need to be cleaned more often. When the water slows down, it's time to clean. Just lift the whole filter unit out, remove the lid and pump at the same time, remove the matting and either wash it out well or replace it. You will also need to run a couple of buckets of pond water over the bio material to remove the large particles. With lava rocks you will need to dump them out every third or so cleaning to really give them a good spray with a hose and replace them every year. With bio balls, you can just dump a bucket of pond water over them, they are very pouris and wash right out and last forever. Make sure the intake holes you made in the bottom of the container are not clogged up. Never use anything to clean your filter but pond water. Just reasemble and put it back in the pond. The "stuff" you wash out of your filter is some great fertilizer for your plants, save it to a bucket and pour it on your favorite flowers, won't burn your plants with little smell that goes away very fast. If you are growing duckweed, use it there. By the way, if you neglect this filter and it clogs, those little pumps will build up enough pressure to cave in the pail and may even crack them. I'm amazed at the power these pumps have.
It takes a while for a new filter of any type to cycle, you can speed this up by using a product like bio boost or use some of the muck from another filter to get this going, in reality, you can just use a quart or so of water from a seasoned pond to give this a jump start. By the way, the water you receive with new fish you have bought is not a good thing to dump into your pond. Not only are there a lot of fish going through this water that may cause a problem, but all of us that sell fish keep the display tank water salted and with health additives that may have adverse effects when mixed with what conditioners you have added to your pond. Mine contains .03% salt (about 1/2 lb per 100 gallons of water) and clear holdex, but most stores and sites will not mention what they use and the sales person may not even know. The salt is mostly to remove parasites and ease the stress on new fish being added. I don't recommend using salt in your home pond if you don't need it for a health reason, the clear holdex will remove the minerals, chlorine, ease stress and help restore the slime coat that may of been damaged in transport. Float the closed fish bag for 15 minutes and then net them from the bag and depose of the water. This is even more important when having fish shipped to you that are in that same water for a longer time. Once you open the bag, do not wait to remove the fish, do not reuse the bags for anything.
Before you start on your filter you may want to stop by and see mine. These are really easy to make, but seeing it will give you a better idea of the complete unit and it's operation, I usually have one out of the tank you can look at. If you have any questions you can contact me at firstname.lastname@example.org If you got here from another site or ad, click here to go to my home page, lots of other free information.
All our information is free for anyone to use. You are welcome to copy and print this information for future reference but not for resale. If you enjoyed the pond and filter builds here at our site you may want to help keep the information on new project coming with a small donation. All information is always free at Tadege.com but it does take considerable time and expense to list it. You are always welcome to watch for new DIY projects for free. Thanks and enjoy your new pond, Tom at Tadege Koi.
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