Non-Gravity-Fed Filtration System

[garywalker]

I live on a ridge and my pond site is underlain by solid rock. Digging the pond hole required a lot of work and I am not willing or able to dig a hole for the filtration system that is even deeper. Therefore I cannot use a gravity-fed filtration system. In this circumstance what is the best layout for the pump and filter system?

Gary

[schildkoi]

Originally Posted by garywalker

I live on a ridge and my pond site is underlain by solid rock. Digging the pond hole required a lot of work and I am not willing or able to dig a hole for the filtration system that is even deeper. Therefore I cannot use a gravity-fed filtration system. In this circumstance what is the best layout for the pump and filter system?

Gary

Gary,
You are making a decision that although is your's to make, may vary well be one that you will regret later and for many years to come. But, like I acknowledged, its your decision to make. I would however suggest that you still do a 4" bottom drain with diffuser and run the 4" line underneath and up the outside of the pond. At least in this manner, should you ever change your mind, the drain and lines will be in place for a gravity fed filter system. Also consider extending the pond up, above grade. This helps in a number of ways including hydrostatic pressures, lessoning of blowing debris into the pond, etc.

There are some pressurized prefilters on the market that you can look at including ones from William Lim and another from GCTEC.

Steve

[garywalker]

Steve,

I am planning to use an aerated bottom drain with a 4 inch drain pipe. My question is what filter and pump arrangement would be best for a system that is not higher in elevation than the pond. It isn't necessary to use a pressurized filter, is it?

Gary

[paladin_k2]

Gary, it sounds to me like you have misunderstood gravity fed systems entirely. The hole you dig for the filters does not have to be deeper than the pond hole. In fact most filter pits are not deeper than the ponds that feed them.

The term gravity fed has to do with the water level in the pond versus the water level in the setllement chambers and filter chambers. If these are well designed there will generally be only a small (on the scale of 1") water level drop between the ponds and each subsequent filter chamber. IN a 6' deep pond there 6' of water stacked up on top of the bottom drain trying to push water out. if the settlement chamber is sitting next to the pond but only 3' deep then when the pond and chamber are connected the water will still push up and into the settlement chamber until the water levels were equalized.

Just based on my experience, if i could not or was not willing to build in at least a settlement chamber then I would not build the pond. You can easily put the pump right after the sttlement chamber and pump the water up into your above ground bio filters (I think Joe of Joeandgabby has some good pictures of the above ground bio barrels).

The problem with taking the shortcut and not doing a gravity fed settlement chamber is that you will need a much more expensive pump and it will wear out two to three times as fast from constantly sucking in and grinding up all sorts of crud. Plus you downstream filter system will have to be moch larger and more expensive in order to contain enough surface area to filter out all the crud that has been milkshaked up into a fine puree.

The settlement chamber being gravity fed from the bottom drain is the primary key to success in the filter design. Remember that this means the surface water level in the settlement chamber is about 1" lower than the pond surface water level when it is running properly. The water at the surface thinks it is flowing downhill even though the bottom of the sediment chamber is often 2 to 3' higher in elevation than the bottom drain.

[schildkoi]

Gary,
If you are not gravity feeding a settlement system first then you will need either a pressurized (negative pressure) mechanical filter before the pump or a positive pressure type filter (bead type) after the pump and possibly before a shower style filter. A few different options including a pumped to Nexus (w/ gravity return).

Steve

[john stevens]

Hi Gary. I went threw a simalar decission with my pond. In the end I had to make the same choice as you are faced with. Almost eveyone agrees it is preferable to settle out solid waste, especially feeces before it can reach the impeller of your pump. In this way disolved organics, and the problems they create may be kept very low. Like you I was faced with having no pond if I had to settle first .For me it was a zonning issue......But, I talked with several successful koi people who were very supportive. One is a well known and respected koi pond builder, another a well known koi judge. Both of whom advised me that you can have a proper pond without settling. The arrangement for my pond system as recomended by both of these fellows is as follows. The 6000 gallon pond is filtered by two seperate parralell loops. Two 3" bottom drains feed two 3500 gph pumps, then each pump feeds a 4.4 bead filter. Then each feeds its own 5 cubic ft bio reactor of moving k1 media, and then back to the pond via gravity. I have had very good resluts. There is also a u.v. in line( that I dont need to turn on anymore) and heater unit from keiren koi in line. A third 4000 gph pump draws water from my skimmer and goes directly to my waterfall. I usually turn that off in winter. You could also add a trical tower or bakki shower if you need too. I have very good water quality. I keep up with water changes, feed good quality food, and dont over crowd. So far so good!

Best of luck
John stevens

[smithvillemike]

at the risk of being called to task.

I don't have a gravity system, but a external pump driven Nexus eazy. It seems to work well from all the stuff I see when I clean it, but it is pretty new.

Mike

[garywalker]

Paladin,

You are correct that I totally misunderstood the concept behind a gravity fed system. I think that I may be able to use a gravity fed settlement tank. How large a tank would be needed for a pond with a capacity of about 4,000 gallons? What would be the minimum height of the tank? My site is on a slope. Can the settlement tank be located at the lower end of the pond and the filter be located at the upper end (I don't think that I have room for both at either end, and the top of the settlement tank would have to be about 3 feet below grade if it were at the upper end).

Gary