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: Filters

Pond filtration is the number one issue faced by pond owners. After 15+ years of doing onsite pond consultations and pond cleanings for Pond Supply I starting building my personal ponds with "excessive" filtration. It was more work and expense up front to set up multiple filters but that was offset by my enjoyment of a crystal clear pond and much less filter maintenance.

By having multiple filters one could be cleaned at a time - that keeps from killing all the beneficial bacteria during cleaning. There are three main filter types - mechanical, biological and ultraviolet filtration.

Video Transcript: Note – this is basically a walkthrough of  the types of filters on this page so rather than watch me do a poor pantomime of the the different filters just listen to me ramble on while looking at the page – sorry about that.

I want to give you a really quick overview of the different kind of filters that you are going to see in ponds. When you are looking at filters or people talking about filters, it is such a broad area. There are different types of filtration. Now, in most pond kits, you are going to get something that is called a waterfall filter. It is basically the lip.  it is the box that has the lip on it that becomes the top of your waterfall, and they add some filtration pads or bio-media or both into that, and that is your pond filter. Now, that works great for the basics and it’s just a starter set and it comes with most pond kits. If you keep the pond a couple feet deep and it is a pretty small area and you run it with a skimmer that comes with the kit - that may be all that you need. But some folks like to add onto those or if you are building your kit from scratch you may be using a different kind of filter. For example, you might want to use a pressurized filter.

Now, pressurized filters are normally buried away from the pond. You have a pump that is either running from your skimmer and that pumps into the filter and from there, it can then, since it is pressurized, it can then go up and feed your waterfall. You can also use an in pond pump that is going to be able to pump some solids, but it doesn’t clog and that would go out to your pressurized filter and then out to your waterfall filter. The main advantage of those is that it can be run in line from your pump to your waterfall and it can be buried. They don’t have to be higher than the falls. Now, with gravity glow filters- what they do is basically they have to set higher.  They have to set higher and up at the top of your waterfall or if you don’t have a waterfall, they would set alongside so your bog or wherever you return the stream back into your pond. The water goes into them they filter your water and then gravity flow back into your pond. They can’t pump the water up - if you try to run them a long distance or up, you can get too much back pressure on them and they will just overflow and empty your pond.

So gravity flow filters are great, but they are kind of hard to hide and if you have a waterfall that you are working with they have to be at the top of the waterfall. Now, in pond filters those are normally used with fountainheads and nozzles. So typically you would have just a box and your pump sets inside of it. It is covered with some filter media or bio balls, something that keep that pump from clogging, and then there will be some piping that comes up and then the nozzle sets on top. Those are great for a very small pond  4 or 5 feet area pond. Those do work fine. The problem with those that you run into is they tend to clog fairly quickly and they are heavy. I mean, they are filled with water and you got to get them out so that can be tough.  if it is something where you don’t want to be climbing in your pond to pull that filter out that may not be the right filter for you. Now, other types of filters would be a UV clarifier and that is typically used in conjunction with a filter. For example, you might run a UV clarifier. Let’s say, if you are using a gravity filter, you would have to use the UV before the gravity filter.

Typically, the UV filters work great if you got them behind your pressurized filter. For example, you would have a pump that runs through a pressurized filter and that gets out most of the big solids. So then you run through your UV filter, so it can do its job as it is passing on up to the top of your water fall. Now, sometimes you are going to see something called a sock filter. It is just a pre-filter. If you have a pump, a typical pump where you stick it in your pond and it is going to clog. Especially those that just have that real fine area where it is going to quickly clog on the bottom intake. That’s bad news because when the pumps get hot, if they don’t have a cut off, they burn out. It is bad news. In addition, using these soft filters can turn those into decent filters for small ponds. So if you have a pretty small pond, let’s say a 4x5 or 5x6 pond and you want to go for something that is the least cost, you might use a pump that you set in your pond inside of a pre-filter, and then run that up to a gravity filter. That kind of becomes your bio-filter in addition to, because you have already skimmed out most of the particulates you know. But you can still use that gravity filters or bio-filter and get it a pretty nice sort of filtration system going for the least amount of cost.

That’s your basic overview. You have your waterfall filters - that basically is the lip going feeding into your waterfall. External filters can be buried and still work with the waterfall. Gravity flow filters are the best bang for the buck, but you can’t really hide them and they have to be up above the highest level of water even if that’s at the waterfall and UV clarifiers work in conjunction with the filters. I don’t think anyone will ever try to do a pond with just a UV filter unless it was a pretty darn small pond.

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