What Filters Do I Need?

[sburtchin]

I'm planning a pond of about 1000 gallons. It will have a skimmer and some kind of bottom drain. I am hoping that I can use a valve to regulate how the water flow is divided between the skimmer and the bottom drain. Ideally, all the filter boxes should be set into the ground and easy to clean so there is not much to do to prepare for winter. I found a sump basin http://www.menards.com/main/plumbin...-trade-18-x-22-sump-basin/p-1444436214906.htm at Menards (about $25) I might be able to use. It is made of polyethylene. Is that safe for fish? This will be a DIY project all the way. Any advice to help me narrow down the choices would be greatly appreciated.

Can you recommend plans for making a skimmer? How do you prevent the animals from getting into it? Should it filter the water too, or should it just have a leaf basket?

Should the mechanical filtration come before or after the biological filtration?

What is a "Skippy" filter, and why is it called that? Is it the same as a vortex filter? What does it do?

What kinds of filters can be cleaned without taking out all the filter media? By back flushing, or whatever.

 

[Mucky_Waters]

I'll give you my opinion on a couple of those questions.
First of all mechanical filtration should always be placed before biological filtration. Mechanical filters should be checked and cleaned regularly, where biological filters hopefully should only need to be cleaned once a year at most. However you'll find that many commercial store bought filters (pressure filters, etc...), and many DIY type filters (like the Skippy filter) tend to combine mechanical filtration and biological filtration to the point where it's hard to tell which is which??? The result is that you'll find you are always cleaning and manipulating the biological filtration material.
A Skippy filter is essentially a flow through box stuffed with a bunch of "filter" material which most people refer to as bio media, but in reality ends up getting clogged with mulm and debris from the pond which impairs the biological activity, to some degree, that you really want going on in a bio-filter, so (in my opinion) it probably functions more as a mechanical filter then a bio-filter. Just how fast it plugs up depends on the size of your pond and how much debris you get in there. If you just have a small,lightly stocked pond and don't mind cleaning it out a few times a year it might be all you really need. Just remember that biological filtration happens on every surface in a pond that the beneficial bacteria can grow on, that includes on the bottom and the sides of the pond, on the plants and algae, in the pipes and rocks, and on the fish themselves, and yes, if you put a Skippy filter in there the bacteria will even grow on the media you put in it too. So if you focus on the mechanical aspect of cleaning your pond you'll probably find that the biological aspect may take care of itself. This becomes less true as your fish stocking rate goes up. The more fish you put in your pond the more ammonia they produce, and ammonia can't be filtered out mechanically, that's where you need help from nitrifying bacteria (biological filtration).
BTW a Skippy and a vortex filter are two completely different things.
The best thing you can do is Google.com Skippy and Vortex filter to find out what they are.

 

[sburtchin]

Thanks for the heads-up on that Skippy filter. The explanations for how that thing works (including suggested vortex action) and how efficient it is are all over the place. In the end after reading and reading, I still just don’t know how or if it works. I know a lot of people swear by it, but please don’t anyone take offense, it seems like a lot of misrepresented science and a little hocus pocus. Let me give an analogy: I have a 50 gallon pond that has had at times over 2 dozen fish greater than 2 inches with a little pump filter box. It plugs up fast in the summer and sometimes I am not able to clean it for weeks. It’s 96F with the sun beating down on the pond (water lilies provide the only shade) and zero water is flowing through the filter media or bio balls, yet the water is crystal clear and no fish are dying. The one thing I can be sure of is that almost nothing was going on inside that filter box. If I had been keeping it clean, I might have thought it was doing exceptional. To answer one of my original questions, I guess the (only) reason it is called a “Skippy” is because the Mom & Pop operation that came up with the idea call it that???

Well, I found out I didn’t know near enough about filtering to carry on a general conversation on the topic. After a lot of reading, including skimming through “ICU2’s Pond Build” which itself took a week (I didn’t know a thread could get that long!), hopefully I can address 1 or 2 narrow topics at a time.

First off, it seems that the Vortex Filter is one option for an essential element of a low maintenance filtering system, and that it should be used with bottom drains. Again, as to how it works, the explanations are all over the place. For example, I read that centrifugal force pulls the solids out of suspension. The water is moving so slow I just cannot believe that. The designs of some DIY vortex filters are wildly different from others. Rather than just pick one of the DIY tutorials that are out there, I would be more confident designing my own based on (hopefully) a thorough understanding of how they should work.

JUST SPECULATING HERE, PLEASE NO ONE TAKE THIS AS FACT:
Let me provide my best guess of how I think these things work, then someone please correct me where I am getting it wrong. A Vortex Filter is a type of settlement chamber. It must be cylindrical. The principle is that a vertical ribbon of water enters the chamber tangentially at the outer wall (or center) of the chamber. This ribbon of water then slowly spirals in to the center (or out to the wall) where it exits. The Coriolis force helps to maintain this spiral flow. It is essential that the flow is entirely laminar. In the process, most solids slowly settle out of suspension before reaching the exit pipe. The cylindrical shape is important to prevent turbulence. The (typical) cone shape at the bottom has absolutely nothing at all to do with the filtering action. It is only there to facilitate discharge of the waste that collects at the bottom. The longer it takes the water to flow through the vortex, the better the filtering action. If the flow rate is too fast, turbulence can form which would break up solid waste and keep it in suspension. A vortex filter would be superior to a typical settlement chamber of equal size where the water can choose its own path because the water in a vortex filter must flow through the entire volume of the container.

Please let me know if any of these assumptions are incorrect.

My main pond will be 1000g. There are a couple little ponds and a lot of stream. I don’t know if those figure into the calculations. For the 1000g pond, I figure at most I would not use a pump greater than 1000 gph. I have a 550 gph pump I would like to use for visual effects, and a 210 gph pump I could use 24/7 if it proves sufficient (there are no fish of any size yet). According to this http://www.clarkekoi.com/pond-filtration.html , for a 1000 gph flow rate, divide by 60 to get the flow rate in gpm, then multiply by 4 to get the minimum size vortex chamber for my pond = 67 gal. This is based on what they call the dwell time of 3 minutes minimum for the water to travel from the entrance to the exit point of the chamber. They claim their vortex filters can remove particulates down to 100 microns, but they do not say what dwell time would be required for that. 3 minutes doesn't seem like very long to settle everything out.

 

[Mucky_Waters]

Thanks for the heads-up on that Skippy filter. The explanations for how that thing works (including suggested vortex action) and how efficient it is are all over the place. In the end after reading and reading, I still just don’t know how or if it works. I know a lot of people swear by it, but please don’t anyone take offense, it seems like a lot of misrepresented science and a little hocus pocus. Welcome to the world of hobby ponds.
Let me give an analogy: I have a 50 gallon pond that has had at times over 2 dozen fish greater than 2 inches with a little pump filter box. It plugs up fast in the summer and sometimes I am not able to clean it for weeks. It’s 96F with the sun beating down on the pond (water lilies provide the only shade) and zero water is flowing through the filter media or bio balls, yet the water is crystal clear and no fish are dying. The one thing I can be sure of is that almost nothing was going on inside that filter box. If I had been keeping it clean, I might have thought it was doing exceptional. To answer one of my original questions, I guess the (only) reason it is called a “Skippy” is because the Mom & Pop operation that came up with the idea call it that???

Well, I found out I didn’t know near enough about filtering to carry on a general conversation on the topic. After a lot of reading, including skimming through “ICU2’s Pond Build” which itself took a week (I didn’t know a thread could get that long!), hopefully I can address 1 or 2 narrow topics at a time.

First off, it seems that the Vortex Filter is one option for an essential element of a low maintenance filtering system, and that it should be used with bottom drains. Again, as to how it works, the explanations are all over the place. For example, I read that centrifugal force pulls the solids out of suspension. The water is moving so slow I just cannot believe that. The designs of some DIY vortex filters are wildly different from others. Rather than just pick one of the DIY tutorials that are out there, I would be more confident designing my own based on (hopefully) a thorough understanding of how they should work.

JUST SPECULATING HERE, PLEASE NO ONE TAKE THIS AS FACT:
Let me provide my best guess of how I think these things work, then someone please correct me where I am getting it wrong. A Vortex Filter is a type of settlement chamber. It must be cylindrical. The principle is that a vertical ribbon of water enters the chamber tangentially at the outer wall (or center) of the chamber. This ribbon of water then slowly spirals in to the center (or out to the wall) where it exits. The Coriolis force helps to maintain this spiral flow. It is essential that the flow is entirely laminar. In the process, most solids slowly settle out of suspension before reaching the exit pipe. The cylindrical shape is important to prevent turbulence. The (typical) cone shape at the bottom has absolutely nothing at all to do with the filtering action. It is only there to facilitate discharge of the waste that collects at the bottom. The longer it takes the water to flow through the vortex, the better the filtering action. If the flow rate is too fast, turbulence can form which would break up solid waste and keep it in suspension. A vortex filter would be superior to a typical settlement chamber of equal size where the water can choose its own path because the water in a vortex filter must flow through the entire volume of the container. Sounds like you got a pretty good handle on it.

Please let me know if any of these assumptions are incorrect.

My main pond will be 1000g. There are a couple little ponds and a lot of stream. I don’t know if those figure into the calculations. For the 1000g pond, I figure at most I would not use a pump greater than 1000 gph. I have a 550 gph pump I would like to use for visual effects, and a 210 gph pump I could use 24/7 if it proves sufficient (there are no fish of any size yet). According to this http://www.clarkekoi.com/pond-filtration.html , for a 1000 gph flow rate, divide by 60 to get the flow rate in gpm, then multiply by 4 to get the minimum size vortex chamber for my pond = 67 gal. This is based on what they call the dwell time of 3 minutes minimum for the water to travel from the entrance to the exit point of the chamber. They claim their vortex filters can remove particulates down to 100 microns, but they do not say what dwell time would be required for that. 3 minutes doesn't seem like very long to settle everything out.

Click to expand the quote box above to see my comments.

You won't ever settle everything out in vortex settling tank, but if you can get everything working right you'll hopefully capture between 80% - 90% of the stuff that would normally settle on the bottom of your pond. And once you've captured it in the bottom of your vortex tank you can eliminate it from the pond water system much easier then if it settled on the bottom of your pond or in some other type of mechanical filter system.

I have basically 3 mechanical filter systems in my pond.
* One is my skimmer basket which essentially only strains floating plant material leaves and occasionally aquatic critters that happen to wander in there. The skimmer basket prevents larger stuff from getting sucked into my skimmer pump.
* Next I have 100 gal vortex tanks that is fed by my 3" bottom drain. Dead algae, fish poop, and just about anything that sinks eventually gets sucked down the bottom drain and flows by gravity only into the vortex tank. The flow rate I have is a little high for the size of my vortex tank, but I have compensated for this by having the flow go into a fine net that captures a lot of the debris, most of what gets through the net settles at the bottom of the vortex tank. To remove the debris in the net I simply lift the net out of the tank and clean it by inverting it and washing it out. The bottom of the vortex tank is cleaned by opening a bottom drain and letting it drain out, and I also have another screen on the outflow pipe which also captures some fine debris that doesn't sink on to the bottom of the tank.
* The third mechanical filter system I employ is for capturing the very fine stuff that gets through the vortex filter. It utilizes a sort of canister wrapped in layers of quilt batting. It works very well for filtering fine particles that float in pond water, it also captures a remarkable amount of tiny pond organisms like dragonfly nymphs and tiny bugs to small to be easily seen with the naked eye. This filter can plug up very quickly at times (especially in early spring) so if I go away for more then a few days I will simply eliminate it from the filter system. It's really not necessary, but it does a fantastic job of polishing the water and giving it that gin clear clarity.

 

[sburtchin]

Vortex Filters – How do they work? Any and all comments to my analysis in post 3 are welcome. I will probably be building one of these if I can find a place to put it. Some of the designs out there seem very different, even some of the commercial ones. Most of the DIY vortex filters have the water entering at the outer wall and spiraling in to the exit at the center. A few have the water enter at the center and spiral out like this commercial one http://www.lagunakoi.com/Vortex/Cyclone-Tanks-p-366.html . On one of the DIY filters, the water enters tangentially at the outer edge and exits through a horizontal slot or spillover at the surface. You could see the water rotating in the tank. I think he was the one who said that in any kind of filter it was critical that the water must enter and exit on opposite sides of the tank. I'm not convinced that's true for all filters.

All the ponders that I’ve read about so far that use multiple stages of filtering have had either a Vortex Filter or a Settlement Chamber as their first filter. Are there other types of filters that are effective for this first stage?

I read a lot about VMS filters. Also that this was a fad that fell out of favor about 5 or 7 years ago because the “SC” filter made it obsolete. I thought “SC” stood for “Settlement Chamber”. Am I missing something? Maybe he meant to say “Sieve Filter”? Is that what made them obsolete?

* One is my skimmer basket which essentially only strains floating plant material leaves and occasionally aquatic critters that happen to wander in there. The skimmer basket prevents larger stuff from getting sucked into my skimmer pump.

Does you skimmer pump go back into the pond, or into the vortex tank?

* Next I have 100 gal vortex tanks that is fed by my 3" bottom drain. Dead algae, fish poop, and just about anything that sinks eventually gets sucked down the bottom drain and flows by gravity only into the vortex tank. The flow rate I have is a little high for the size of my vortex tank, but I have compensated for this by having the flow go into a fine net that captures a lot of the debris, most of what gets through the net settles at the bottom of the vortex tank. To remove the debris in the net I simply lift the net out of the tank and clean it by inverting it and washing it out. The bottom of the vortex tank is cleaned by opening a bottom drain and letting it drain out, and I also have another screen on the outflow pipe which also captures some fine debris that doesn't sink on to the bottom of the tank.

Does this net wrap around the pipe like a sock where the water enters the tank? On the outflow pipe, is that just a screen (with relatively large holes) for capturing floating debris only? Does it plug up?

 

[Mucky_Waters]

sburtchin said:
All the ponders that I’ve read about so far that use multiple stages of filtering have had either a Vortex Filter or a Settlement Chamber as their first filter. Are there other types of filters that are effective for this first stage? You mention one type below. Sieve Filters They are probably more effective that settlement filters or vortex filters and certainly have the smallest footprint. The down side is that they are kind of pricey.

I read a lot about VMS filters. Also that this was a fad that fell out of favor about 5 or 7 years ago because the “SC” filter made it obsolete. I thought “SC” stood for “Settlement Chamber”. Am I missing something? Maybe he meant to say “Sieve Filter”? Is that what made them obsolete? What is a VMS filter?


Does you skimmer pump go back into the pond, or into the vortex tank? No, my skimmer is plumbed with a 1" line that goes from the skimmer to the pump, to a UV unit, to a Phoam Phractionator (protein skimmer tower), and then into my biological filter tank. It bypasses the vortex tank.

Does this net wrap around the pipe like a sock where the water enters the tank? Yes exactly.
On the outflow pipe, is that just a screen (with relatively large holes) for capturing floating debris only? Does it plug up? Yes it is a screen that has holes about the same size as the sock net. Before I employed the sock net it use to plug up fairly quickly, but with the sock net in place I can go for weeks without changing it if I want. But I still clean it just about as frequently. I believe in cleaning the debris out of the pond cycle as often as my time allows. If you don't remove the stuff from the pond water circuit it really doesn't mater if it's in the filters or in the pond, it will eventually break down and dissolve into the pond water as DOCs and ammonia, nitrate and then finally nitrogen if you leave it in the filters long enough.

 

[Lisak1]

What kind of fish do you plan to keep in your pond? 1000 gallons is on the small side for koi; perfect for goldfish. If you plan to keep goldfish then I think you may be overdoing it on filtration. Just an opinion, (and maybe useless if you do plan for koi!)

 

[sburtchin]

You mention one type below. Sieve Filters They are probably more effective that settlement filters or vortex filters and certainly have the smallest footprint. The down side is that they are kind of pricey.

I think I could make something like the Ultrasieve III http://www.absolute-koi.com/prod901.html
for about the same cost as a vortex with some caveats. I haven't yet found a source where the wedge wire screen is not terrifically expensive. I don't know if woven wire mesh can be used. Also, it looks to me like there is a lot of head loss with that type of filter, and there does not appear to be much volume for waste to collect. I wonder if it needs attention every few days.

What is a VMS filter?

That was not a good choice for an acronym, it already being in widespread use for something else. I stumbled across it: "Vortex Micro Screen". I'm not yet sold that it won't defeat a great deal of the function of the vortex. Also, a lot more complication. A good tutorial here: http://www.koiquest.co.uk/forum/viewtopic.php?t=2436 and some more indepth discussion here: http://www.koiphen.com/forums/showthread.php?19153-Air-Lift-VS-Spray-Bar&pp=10 . I read somewhere it was an obsolete fad, replaced by the "SC" filter in the DIY community. Maybe he meant to say "Sieve Filter? The only thing I could find for SC was Settlement Chamber.

What kind of fish do you plan to keep in your pond? 1000 gallons is on the small side for koi

Mostly koi and a few goldfish. I would like a few turtles too, and we get lots of frogs that come voluntarily. This is more an addition to my gardening hobby than me being a fish guy. I want an escape from the plain lawns and chain link fences. The more animals the better, above and below the water line.

I know someone who has 3 koi over 12" in a 10 gallon bucket. He bought them as babies. The water circulates through a filter and one of those antique hand crank well pumps. It's a yard ornament. The water turns over probably 20 or 40 times per hour. Those fish struggle against the currents. Not my kind of pond, but it blows away the concept of minimum sizes. I wish mine could be about 4 times bigger, but then I have to eliminate some trees.

 

[Lisak1]

Mostly koi and a few goldfish. I would like a few turtles too

You definitely want good filtration then, if you plan to overstock a pond. People do it - you will just spend your life managing water quality. And "a few goldfish' will quickly become legion - before you can blink you'll have multitudes.

3 koi in a 10 gallon bucket is beyond dumb... it's cruel in my opinion. Plus, how can it even look good? Three fish stuffed in a bucket... ugh. Sorry. Can't find anything good to say about that situation, so I probably should say nothing at all.

 

[sburtchin]

3 koi in a 10 gallon bucket is beyond dumb... it's cruel in my opinion. Plus, how can it even look good?

Cruel is probably the least you can say. May have been 20 gallons tops, but I remember only the fish in the middle was able to straighten its body. Three plastic koi and some algicide would have served him well. From the street and pulling up the drive the look is awesome - an old stone well with an antique spigot gushing water. As for the fish being stuffed in there, I am with you. I don't know why he would want fish and not provide a proper home next to the patio. Why do some people mistreat dogs the way they do? BTW - just somebody I know, not in my circle of friends.

You definitely want good filtration then, if you plan to overstock a pond.

How many gallons are recommended per fish? Or maybe I should be asking how much filtration per fish or turtle? I plan to stuff it with plants, so it should be an stimulating home, even if on the small side.

 

[Lisak1]

Gallons per fish is only one part of the equation - and you'll find varying answers. Some people say 1000 gallons for the first koi and another 250 for every one after that. Some will quote gallons per inch of fish. Others will say that an inch of goldfish is not the same as an inch of koi. You also have to consider the surface area of a pond. A pond that's 4 feet by 4 feet and 8 feet deep is almost 1000 gallons, but the surface area is far less than a pond that is 4 feet by 10 feet and only three feet deep... which is also close to 1000 gallons. And I know nothing about turtles at all, except that those who have them say they are heavy waste producers and will dirty up a pond big time. Maybe @Mmathis will chime in here on that subject.

My personal opinion is that every pond owner should strive to stay WAY BELOW any minimum that you can find - no one has ever said "gee... my fish all died because I had TOO MUCH POND!"

 

[sburtchin]

Thanks! I will reevaluate my land usage to see if I can tweak out any more area to devote to pond water. I already have the raised bed strawberry patch, the 10' x 25' trellis, the raised bed vegetable garden, about 15 fruit trees (I haven't counted lately), lots of ornamentals, the 12' x 24' barn, 3 stall compost bin, other stuff and plans for a gazebo. It's a bit crowded.

As planned, my pond is approximately 7' x 12' x 4' deep irregular with a plant shelf around the perimeter. Also, multiple plant shelves at varying depths. The big fish will also have access to explore the stream below the 'little fish' pond. There is also a 'baby fish' pond and waterfall upstream from that. I am trying to create a natural and interesting environment for the fish. I thought the volume was going to be much greater. It's still just a hole, so things can change.

I have read posts from many ponders with massive filtration systems for not-so-big ponds. I can only think that they must have a lot of fish, like the guy with the 2000 baby koi as he termed it, all over 2". That's a massive amount of fish. I don't ever plan to have near that much.

If I increase the width of my pond, I will have to take into account what widths of liner I can get. I don't want any seams in the pond. I would not want to have to waste an 8' wide strip of liner. I already have plenty of liner I can use for the streams.

 

[addy1]

I bought my liner from bend tarp and liner in oregon. it is ppl36, they cut it to the size I needed, which for me was around 55x35 If I remember right.

 

[Lisak1]

If those are your pond dimensions, that's more than 1000 gallons - more like 2500 give or take.

 

[sburtchin]

The plant shelf around the perimeter is on average 9.5" deep. So 7' x 12' x 9.5" x 7.48 gal/cu-ft / 12"/ft = 497 gal for the top layer of water. The plant shelf is about 14" wide, so below that, the pond dimensions are roughly 4.7' x 9.7', and the bottom depth is 44". The end has a series of plant shelves, so the average length is actually about 21" shorter. The walls have some slope to them, so the average width AND length for the deeper water is shortened by about 10". So 3.9' x 7.1' x 34.5" x 7.48 gal/cu-ft / 12"/ft = 595 gal for the deeper water. Adding the two we get an approximation of 1092 gal. I have a 3D model in AutoCAD, so to be way more precise than I could ever calculate by hand, I let the computer do it for me. It will hold exactly 1020.6 gal as planned. I hope I remembered that conversion factor (7.48) correctly. Like I said before, I was surprised by how little water volume I ended up with.

I brought up the yard ornament example earlier only as an example to illustrate that volume restriction, no matter how extreme, must be far less important than water quality. I have read that pond volume is a limiting factor in how big a koi can get. Clearly that is not the whole story.

Humane examples of relatively small volumes in proportion to their fish populations can be found on this forum, like the guy with 2000 'baby' koi and this guy who pumps 4,300 gph through his 435 gallon pond. They both have massive filtration systems to maintain good water quality.

One thing that does concern me is that at the deepest part my pond is not very big. I don't know if koi need a lot of room to swim around at that depth, or if they just need it as a place to hide or rest. I hope that by having lots of plants, the fish will feal less constrained by the size of my pond. In regards to total volume, does this in any way limit how big a koi can get?