5 Year Member
- Nov 16, 2013
- Location (City and/or State)
- Santa Cruz, CA
I thought I would put in filter design here. It could go anywhere in the chronology as every step of the way requires attention to different elements the filtration will require.
Every step of this project had to account for the filtration I had designed. The Electric run for the pump, aeration, and ultraviolet filters. The plumbing for fill line, drains, skimmers, pump return to waterfall, all had to be planned and placed for proper water circulation. Great water quality is not only a requirement for me to ensure the health of my turtles and fish, but without perfectly clear water, the window features I have prominently in the plan are rendered useless and an eyesore!
Over the years, and the 7 different ponds I have built for myself, I have tried many different ideas and done countless hours of research on filtration. I have ended up with and feel most confident in the biological, gravity type filter I have come up with after several different versions. I use gravity flow to push water through a balanced flow from two bottom drains and two skimmers I place at opposite ends of the pond to ensure a minimum of possible “dead spots” in the pond so all the water circulates without areas of no circulation. The pump I use is extremely energy efficient for the volume of water I want to circulate. I like to size the pump to turn the volume of the pond in 1-2 hours for best filtration. For a 10,000 gal pond, I am using a 110 gal/minute pump. That will give over 6000 gal/hr, so the volume of the pond will turn in less than 2 hours 24/7.
Most all pumps I ever see offered at pond supplies do not work for me. To get that type of GPH, they always use at a minimum a 1 HP pump. That would normally draw about 1 – 1.2 Kw to run. When talking cost to run electric appliances, everyone uses an “average” cost of electricity that has nothing to do with the actual cost in California! In most of California, if you are on PG&E, you are paying 37¢ per KWH. They do have tiers to the cost structure, but minimum normal household use will take you over the lower rates, so adding a pond is always adding on top of useage that is already over to the top tier. So, doing the math – 1.1 Kw X 24 -= 26.4 KWH. Times 30.5 average days per month = 732 KWH per month to run. At 37¢ that is $271 per month to run the pump!
Years ago, I was consulting with a koi breeder who used water radiator heating circulating pumps for his ponds. These are pumps designed to be used in homes and factories to circulate water 24/7 and run for 30 years or more. Very high volume, lower head pumps and extremely efficient. This is the type of pump I use. My 6600 GPH pump is 1/4 HP and draws 330 watts. Plus, this new pond, in the Sacramento area is in the Sacramento Municipal Utility District, not PG&E!!!!!! SMUD charges 1/3 the rate PG&E charges. So now .33 x 24 x 30.5 x 12.9 = $31.16 per month to run the pond 24/7. That is much better!
For those interested, this is the pump I use. It is a Bell & Gossett series 2 ½. They come in all different sizes. I’ve used their 1/6 HP and 1/12 HP pumps on previous ponds. You will not find another pump that will pump anywhere close to the volume of water as efficiently.
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The way I do it, the main filter chamber has to be at water level as gravity feeds water into it. Here is the filter chamber I am building at the far right. Water level is 12” higher than the ground level (grass area) in the adjacent tortoise yard.
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Since 6000 GPH is flowing through this, I need enough pipe size coming into the filter chamber to minimize the drop in water level needed to push enough water in. I calculated I needed at least 2 - 4” pipes to give a 1” water level drop. So I used 3 - 4” pipes to give a nice margin to be sure. Here are the 3 – 4” ABS pipes I am using to feed the filter chamber. I am running one from the near bottom drain and up through the near skimmer. Since both are quite close to the filter, I have combined them both into the same line on the left. The middle line, I am running to the other bottom drain. So I had to run the line under the pond. All Jackhammer work for the line and drain! The line on the left runs around the perimeter of the pond to the far skimmer. You can just see the skimmer sticking up right next to the sipping pool. Since these were longer runs and I wanted to balance flow, they both are on their own 4” line.
I am standing in the filter taking these pictures…
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Here I have backfilled the 4” lines and installed the pump impeller housing for the return line to the waterfall. I am using a 2 ½” pump, but using a 3” return line to reduce head pushing water to the waterfall. I am only lifting water 3 feet to the waterfall chamber, so there is very little head loss at all with this system. Here is the filter chamber with pump impeller housing installed on the far right. The 3 – 4” lines run under that. The 3” line (black ABS) to the waterfall is going off to the left. You can see the electric conduit (grey) and the white water lines for irrigation and fill line.
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Here is a finished view showing the filter chamber and you can see how I incorporated it into the wall and stairs to the upper patio I built at the top of the stairs. The 3” line pushing water to the waterfall runs from the left side of the filter chamber, under the upper patio and part of the upper pond, to the waterfall in the far back center in this picture.
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Here, I have now done the masonry work and have the wall outlining the upper patio on the right, with the wall for the back of the pond area leading to the waterfall that is taking shape on the far left.
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Since I need vertical wall and no possible escape routes for turtles, I constructed the waterfall itself from mortar that I hand shaped to resemble rock. Here I already have set the real rock for the top edging of the upper pond, and have started shaping the wall of the waterfall. You can see the chamber above the waterfall the water from the filter pumps into. That Upper chamber will have plants sitting in it to let the roots grow and create a natural filtration, consuming nitrates and lots of bacteria growing on the roots. The water spills over creating the waterfall.
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Some more brown color for a deeper color texture…
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Then add some more black and just a bit of white to match the natural rock I am using…
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Once you add some plants, and plaster coat is done, it starts looking like a real waterfall…
The upper chamber above the waterfall is big enough to place some large plants the turtles cannot get to. That provides great additional filtration as the roots grow and fill in a lot of that chamber.
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The main biological filter is the filter chamber itself. Since this is the heart of the biological filtration, I thought I would also show the diagram I made of how I built it and the design concept.
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You can see the 3 – 4” inflow pipes on the left. A raised ledge is built creating a chamber inside that is capped with a piece of ½” plexiglass. I have 35 - 1 3/8” holes drilled in the plexiglass and have 1” threaded fittings screwed in around the plexiglass in each hole. The water flows in through the 3 – 4” pipes. A pair of Matala pads will create a pre-filter against the ledge, and the water will then flow through the Matala pads to the main chamber. It will then flow through foam pads on each of the 35 1” pipes to the area below the plexiglass. That is then drawn to the pump through the 3” pipe you can see At the top of this picture under the plexiglass. I cut multiple slots in the 1” pipe for good water flow through the foam pads that slip over these pipes.
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Following are pictures I just went out and took to illustrate things in operation as they are today.
Here it is in operation. I use a 1” pipe with a threaded fitting I can adjust to friction fit between the front and back wall to hold the Matala pads in place. The Matala pads filter out the bigger debris. I have a coarse (black) stacked against a medium (green) pad. I built the filter chamber exactly to fit a standard full pad. They are 39” wide and 24” tall. Those two pads alone are rated to filter about a 1200 gal pond. The foam pads are 4 ½” square and 12” tall. They are the basic style the real old “green machine” pond filters were based around. An old Green machine for a 5000 gal pond had 6 of these pads in it. I use 35 here. So in a chamber that is 39” x 45” I have what a manufacturer would rate at probably a 30,000 gal+ pond capacity. Lots of surface area for beneficial bacteria to colonize.
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I addition to the filter itself, all the pond surfaces will become colonized with a biofilm of beneficial bacteria. I have found it takes about 2 years to really establish a new pond and see the true results of the entire design. I also rely on plants to provide a big boost in filtration. My chamber above the waterfall is filled with plants living off the nitrate “waste” produced in the pond. The roots fill the entire chamber and I have to thin out to roots a few times a year to ensure proper water flow, but it works fantastically.
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The upper pond is also filled with plants. My design idea was to make this a habitat for the spotted turtles in addition to making a “bog filter”. They love to stay in shallower water and hide amongst plants. I hoped the larger cooters would stay below and leave the plants alone. It works perfectly! The plants thrive and add tremendously to the filtering. The spotted turtles love it and stay up here.
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I even stick a plant in the skimmer to let the roots grow with the water flow. This is a tuber from an elephant ear I just stuck in the water in the skimmer, propped in place with a block, and let it grow.
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I also built a small “reef” of blocks and rock with some aquatic planters zip tied together forming a sunken island. The umbrella plants are in coarse gravel, so the roots only have pond water to feed off.
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Aeration is also key for a healthy pond. I built the waterfall as a 2 step main waterfall to maximize the aeration from the 6000 GPH of water flowing over the falls constantly.
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I also installed two large aeration plates in the pond. This makes a huge difference in water quality. It is amazing how much this improves the oxygen content of the water. When installed you can immediately see the difference in the way the fish act!
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The water flow is through the upper pond, creating a nice bog filter. It’s flow is split into two streams that then feed the lower, and much larger main pond. I designed the streams and their outflow to create a subtle, but distinct current that ensures the water mixes throughout the entire pond, before returning through the two bottom drains and the two skimmers to the filter.
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I have 3 UVC filters the water also flows through as it enters the chamber above the waterfall. Flow rate is extremely important for a UV filter and if the flow is too swift, there is not enough “dwell time” in the UV filter tube where the water is exposed to UVC. I use 3 - 40 watt UV filters. They are designed for an optimum flow of 1500-2000 GPH ea. At the lower end you actually get a bit of a sterilizer effect, helping to kill off possible bad bacteria that could effect the Koi. So I split the flow into 4 going into the waterfall chamber. ¼ of the flow goes into each of three UV filters, and ¼ goes into the pre-waterfall chamber directly. So in effect, I have about 1500 GPH going through each of the UV filters. During the first two years of getting a new pond established, this is a great way to eliminate problems with the green water algae blooms that are otherwise inevitable. I do not have these turned on in the winter months at all. And now, with the pond finally established, I really don’t use them much at all. But they helped tremendously, especially the first year.
I couldn’t be more pleased with the way the entire filtration system is working. June this year marked the 2 year anniversary filling the pond. So I do now consider it fully established. This summer, with record high temperatures and 100°+ days, the pond remains completely clear, with fish and turtles thriving.
I’m sure there are filters systems now that are much less time consuming to clean. I do spend, in peak summer, about 1 ½ hours a week cleaning the filter pads and trimming back roots. Some of the new filters are more a pool type filter, that you just backflush for the weekly maintenance. However, I am reluctant to try something when I know what works so well for me. I would like to find something less maintenance intensive for the long term, but then the high pressure pumps and energy consumption that Comes with that also concerns me. For now it is an ongoing research project I am keeping my ear to the ground and see if something intrigues me enough to perhaps convert. I know what I have now works. Works really well. And we really enjoy our pond!
Next up… Building the pond shell, with windows and making waterproof.
Amazing thread Mark. Going to do some research on those pumps. Running 5 ponds right now so those would be a great help.