trickle filters

[Mmathis]

Is a trickle filter the gravity, downflow type? I'm still a little confused since there seem to be such variation in bio filters. Is a trickle filter even considered a bio filter?

 

[Catfishnut]

Is a trickle filter the gravity, downflow type? I'm still a little confused since there seem to be such variation in bio filters. Is a trickle filter even considered a bio filter?

M,

I am also not clear on the title and variation here, either. I thought someone here explained it, but then I noticed others referring to it differently from time to time. I personally think of a "trickle filter" as a vertical column or possibly a sleuce filled with media where the water "trickles" down through it. The media is not entirely submerged in water, the water flows over and through it. I may be mistaken, but that is just what I envision in my mind when the term is used.

The other style that I think of is where water percolates upwards through the media and overflows out of a box through a pipe or out directly into the pond via a sort of waterfall mechanism. The names "Skippy Filter" and "Doc Filter" come to mind.

Either way you refer to them, they are all really a "bio-converter" and not truly a filter. A filter would be mechanism for separating or trapping debris and sediments from the water and letting the clean water pass through. Whereas a bio-converter scrubs the ammonia and the nitrites from the water by using the bacteria colonies that grow on the "media". They can "filter" too, but that is not their intended purpose and if you rely upon them to filter a lot of sediments and muck from the water, the media can clog up and the water flow through them will decrease over time until they are plugged/clogged. If they become plugged up, you may have to clean them and that is not good because you will also be cleaning (removing) a lot of the desired bacteria at the same time.

For my bait tank, I am applying what is termed a "moving bed, bio-converter". This is where the media (small, semi-buoyant plastic discs) cycle around in the filter tank like boiling noodles with the use of bubbled air and or flowing water. The bacteria live on these discs. The discs look like Honeycomb cereal, to describe them as best I can. A moving bed filter or converter can be made from anything (sand, gravel, plastic beads, plastic discs, etc) as long as it moves and circulates to some extent.

Gordy

 

[Waterbug]

As Gordy said, "trickle" filter refers to water trickling over media. The idea is to keep the media clean and add O2.

The most basic trickle type filter is a stream, water moving over rocks. Turning the stream vertical is called a trickle tower, you get a lot more surface area, cleaner media. So a 3' tower might perform the same as a 12' stream.

The next generation is the shower filter. Basically the same as a trickle tower but with a shower head which allows more water to be pushed through. A Bakki shower filter is a shower filter with Bakki media.

There are 2 basic types of filters imo. Bio and mechanical. A bio filter is any thing that serves as a home for bacteria colonies. Normally the target bacteria is for converting ammonia and to a lesser degree, nitrites. However it could also be for bacteria that kills algae.

A mechanical filter physically moves chunks and particles. Normally these would be mesh and pads type deals. But can also be vortex type filters and settling tanks.

In the hobby world combo units are popular. A pad is suppose to be home to bacteria and also collect particles. Sounds great...but collected particles bury and kill bacteria. So you won't see combo filters much in fish farms and fish keepers with high fish loads like high end Koi ponds. The closest combo high end filter is the bead filter but I think that has been replaced with fluidized bed filters. In the bead filter the beads remained stationary trapping particles and had to be flushed often. The fluidized bed is basically the same except the beads are kept moving so no particles are trapped and the filter almost never needs to be cleaned.

That's kind of my own definition of filters...if you have to clean it then it isn't a bio filter, or at least a very good bio filter. Which is why I don't think much of Skippy. A lot of people swear by them but I don't think they're used in ponds that actually need any bio filter.

 

[Mmathis]

What's the least complicated way to set up a "settling tank" (or other way to catch the bigger pieces of debris) before that water gets to the bio media? Physical space and a limited brain are issues

 

[Catfishnut]

What's the least complicated way to set up a "settling tank" (or other way to catch the bigger pieces of debris) before that water gets to the bio media? Physical space and a limited brain are issues

M,

I know that I have posted this here somewhere on the forum, but I don't recall where or to whom I was responding.

Anyway, the most effective, efficient and maintenance friendly system for removing solid wastes and debris from the water as a "prefilter" or "settling filter" is through the adoption of the same principle that is utilized in septic tanks for homes.

It is a very simple design and very easy to build and to maintain.

The discharge water from the pond is let into a (let's say a barrel or drum for simple discussion) via a 2" PVC pipe. This pipe enters the drum up high - maybe 3/4 the height of the drum. The outlet of effluent water exits the opposite side of the drum just an inch or two below the level of the inlet pipe.

Inside the drum, on the inlet side, the incoming PVC pipe is connected to a "sweep tee" fitting. You know what a "Tee" pipe fitting looks like, that is easy to envision, just think of the letter T. A sweep tee simply puts a "curve" in the center port of the tee that faces or directs water flow to one side of the top of the T. That curved portion is directed downwards into the drum and a length of PVC pipe is connected below the T to force the water and sediments towards the bottom of the drum. The other side or the top of this T is left open to the air space at the top of the drum. Maybe a short piece of PVC pipe is attached (just a few inches) to prevent the water and sediments from overflowing here, it is meant to be just a vent to prevent a vacuum area here.

On the outlet side, the identical connections are made with another sweep tee.

The difference between the inlet and the outlet sides are that the outlet pipe is one or two inches lower than the inlet pipe AND, the pipe that drops down towards the bottom of the drum is shorter on the outlet side. Hence vertical PVC pipe on the inlet side may stop two to four inches above the bottom of the drum, but the vertical PVC pipe on the outlet side stops six to eight inches above the bottom of the drum.

Try to draw what I am stating out on a piece of paper and it may click in your mind what is going to happen with solids and sediments here. The solids that are heavier than water will sink to the bottom of the drum and cannot find the outlet or exit pipe. Those that are lighter, will float to the surface, but cannot find the exit pipe, either. Hence they are trapped! Natural bacteria will develop in this tank and break down the waste products into a safe sludge.

In a septic tank system, it is intended that the top of the drum be opened and the sludge "sucked" out with a pumper truck. For a system like this being used for a pond, you can fit a drain line at the bottom of the drum and just open a valve and purge it out, water and sludge and all, into your garden area and use it for good fertilizer.

This sediment or solids filter is so very simple to construct and there are no pumps or mechanical devices to contend with, except the valve to open and close the drain line.

You can make this more elaborate by adding baffles in the space between the bottom of the inlet pipe and the botom of the outlet pipe if you wish. Baffles will break the flow of the water so that the lighter solids and sediments will drop out at the bottom of the drum more easily. A few layers of the ceiling lighting grates stacked so that the holes are at different angles should be enough to slow the water flow so that more of the finer, but heavier than water debris, settles to the bottom more readily.

It's a similar principle to a snow fence. If you put up one snow fence, it cuts the speed of the wind and the slower the wind is, the less snow it can carry with it, so the snow drops out of the air in front of the fence. Put up another snow fence downwind from the first, and you drop out even more snow. Put up several snow fences in parallel lines (perpendicular to the main wind direction) and all the snow drops out of the air before it drops out over your road or driveway. Hey! No need for a snowblower!

It is all mechanical physics. But, don't let the principles of physics scare you. They are simple laws of nature that you witness everyday, just put them to use for your own benefit. Let NATURE work for you! It is so simple in theory and so simple in design and construction.

You do not require a huge amount of space and you don't have to be a great wizard to accomplish this. Just a little time and effort and some cheap PVC pipe and some water holding vessel. Could be a drum or a rubbermaid box container or an old water heater tank, etc. Whatever you can get your hands on. The taller the better, but I wouldn't go taller than 3-4 feet or shorter than 24 inches. Depends on how much water you are servicing and how fast.

Does my idea register well with you? Or did I lose you along the way? I can clarify anything if you like, just holler at me or research septic tank designs.

Gordy

 

[Catfishnut]

M,

Here is a pix of a sweep Tee fitting.

Gordy

 

[Waterbug]

Easiest imo is using the pond as a settling tank.

But I think most people prefer a separate deal which is more expensive, less effective but has the advantage of being something they built. And that's an important component to any hobby. A hobby is for fun and sometimes building a complex filter system is important.

Here's a couple more designs.

 

[minnowman]

Waterbug,Bead filters do a pretty good job as a combo filter. Thats all I have on my first greenhouse[the one with the concrete floor]. If it isn't big enough for the fish load when the Koi get big I'll just add a moving bed biofilter with Kaldnes K-1 media. It's simple to build and has almost no head loss. The only maintenance is cleaning the air stone occasionally.

 

[Catfishnut]

Waterbug,Bead filters do a pretty good job as a combo filter. Thats all I have on my first greenhouse[the one with the concrete floor]. If it isn't big enough for the fish load when the Koi get big I'll just add a moving bed biofilter with Kaldnes K-1 media. It's simple to build and has almost no head loss. The only maintenance is cleaning the air stone occasionally.

Minnowman,

I am also using the moving bed bio-converter with Kaldnes media, but I am using the K-3 type. As you probably know, this for me is still in the construction phase. Ran out of nice weather to get it completed before winter weather started scaring me off. I didn't want to get caught in a snowstorm with all my stuff in disarray out in the yard.

Prior to the moving bed bio-converter I am using a prefilter or sediment filter with essentially the same design principle as the septic tank concept, but with coarse rock for baffles. I may alter this before I actually finish it and adopt the use of some baffle material like the lighting grates or something just as effective as the rock, but with much less weight. That would make maintenance much easier in the future for me.

Gordy

 

[Catfishnut]

M,

I have attached several diagrams of very simplistic septic tank designs below so that you can see what I am referring to. Notice that some of them show a vertical wall with a porthole or overflow in the midsection. That is what I refer to as the baffle. I am not placing my baffle like this. Mine will be laying horizontally somewhere in the midsection of the drum, and it will be full of many portholes.

Due to space limitations and in order to simplify my own construction, I have basically rotated the septic tank designs depicted below so that they are vertical, with the inlet on the very bottom and the outlet on the top and the baffle in the mid-section. Then, instead of pumping the system out from above, I flush it out from the bottom through the drain line. (Drain line not shown in the attached pix).

The design that you may use for a sediment trap or settling filter can vary greatly from what these pix reveal, but the general concept is the same. Slow the water flow so that the sediment drops out and the water continues on.

Fast moving water can carry a great amount of sediment and debris (and of course, fish and turtle poop). By forcing the water to slow down, it loses its energy and therefore must drop its load of sediment or solids. With the inlet, outlet, drain and baffles positioned correctly, you can devise a really great sediment filter for your pond or turtle tank. Most of all the solids will be deposited at the bottom of the drum and you can flush them out quickly at any time by just simply opening the drain valve for a short time.

You will be able to tell how well the system is working by seeing how much sludge comes out when you open the drain. Compare that with how nice your water appears at the outlet of the sediment filter as it goes into your next filter stage.

Please note, in all of these diagrams, they show that the outlet or the effluent water discharge to be at a lower level than the inlet. That is what I stated that should be adhered to and it agrees with my thinking. However, they also generally show the vertical pipe that drops down from the outlet tee to be lower or at least at the same height than its counterpart at the inlet tee. This part of the design I disagree with. My own personal experience has proven to me that it works better for these two pipes to be reversed. Lower to the bottom at the inlet and higher at the outlet. Remember, the outlet pipe still must be lower than the inlet pipe, it is how far the bottom the "drop-in tube" and the "pick-up tube" are below the tees that I am referring to.

Keep in mind that we are talking about a modification to the septic tank design so that it can be used for a pond filter. We have changed one major parameter here. The water is continuously flowing in our pond system. In a septic tank system, that is not the case. You are not flushing your toilet continuously. This makes a great difference in how the water flows in the sediment trap versus a septic tank.

With continual water flow, I found that the sediment can find its way to the outlet "pick-up" tube if it is too low in the sediment chamber. It has to be higher up in the cleaner and slower moving water. The lower to the bottom of the drum, the more turbid the water will be, you don't want to siphon from this zone or layer or else you will be defeating your purpose of the design.

Gordy

 

[Waterbug]

Minnowman, I think there are more studies on bead filters than any other filter used in ponds. They do work, just not as well as breaking up the task into separate filters each being the best possible for doing a limited job. In hobby ponds combo filters are fine because very few hobby ponds have any need at all for a filter to convert ammonia. And removal of particles is not important either. As long as the pond keeper see some trapped stuff that's good enough for them.

If I might use Gordy's example...Gordy, you will be very happy with your settling tank design because you will see stuff collected. Perfect hobby set up, looks great on paper. I'm guessing Gordy is not going to measure DOC or TOC, C02, or even O2. As long as the only measurement done is eyeballing pretty much any filter will be deemed as great. And that's fine for hobby ponds when filtering isn't even needed.

For people trying to earn a living growing fish they actually need filters to perform at certain levels. They measure O2, C02, DOC, TOC, ect. To them data from studies is a more important source of information than someone's opinion with no data. They do listen to opinions, but then research and test for themselves.

I think filters for hobby ponds are in their own class and have unique criteria such as being fun to build, looking and sounding impressive, being inexpensive. Performance, although trumpeted often, is almost never important enough to even bother to measure. I think there's been exactly 0 studies on the Skippy filter for example, a filter widely used for hobby ponds but in no other field of fish growing.

My opinions on filters geared toward studies and unfortunately ignore the important criteria of hobby pond owners.

 

[Mmathis]

Gordy -- um, I think I'm the person you recently posted the explanation for ... But I ALWAYS appreciate repetition! Repetition and pictures are my friends

 

[Shdwdrgn]

... but I always try to block all sunlight for the benefit of the bacteria.

This is the first time I've heard of this. Is beneficial bacteria sensitive to sunlight? I've always built my skippy filters with the top of the barrel cut wide-open. I hate to think that I may have been killing off the top layer of bacteria all these years? And just *how* sensitive are they to sunlight? I use white barrels which also allows some light to get through the sides.

 

[sissy]

where I bought my koi was the one who told me to use dark color for the filter and if yo don't have a lid for the barrel use a garbage can lid or plant in a thick doubled up net plants and just trim the roots often so they don't grow down to far into the filter .He had a large open filter with tons of water hyacinth growing in the top of his

 

[Waterbug]

Nitrifying bacteria are photosensitive but they do have some defenses. I wouldn't worry too much if the filter has been used for years, and ammonia has been zero, because apparently whatever bio filtering was lost was never needed.