filtering the fancy goldie pond

[cowiche ponder]

This was a question posted on a koi forum (koiphen) where there is a fair amount of chat on goldies. The question was asked about bottom drains and goldies. The seem to get sucked to or even into the bottom drain. Even with a settlement tank after the bottom drain it is very hard on our finny friends (I did have a koi that seemed to enjoy it?) Same with a skimmer on the side.

I think the skimmer problem can be addressed with a no niche skimmer instead of a savio type skimmer.

Someone mentioned putting in a pvc pipe with 1" holes drilled into it as a retro type fit, one that can get the crud off the bottom, but with the flow distributed evenly enough not to tend to suck in fish.

Any ideas here?

Mary

[Fishdork]

My pond is 3 1/2 ft deep. Pond is surrounded by grape vines and large cherry tree. I used Tetra pond drains. The first time they're taken off to get leaves out, it's nearly impossible to get them aligned on the posts again. I used to have koi and goldfish up to 6" long go through the drains. Finally cut the rims off 5 gallon bucket lids and caulked them upside down onto the drain cover to reduce the size of the gap. Now I rarely get a fish in the sump, usually 4" or less.
I put a nylon coated coffee mug hook (no scratched fish) into the top of each cover so I can lift them off with the rim of a long handled net. I just put them back so they cover the hole, the posts aren't going to line up still.
Stick your fingers under the covers and decide how much space there is and find a non toxic spacer that won't restrict flow to your pump too much. (styrofoam dissolved after a couple years).

Norm

[cowiche ponder]

Thank you for input!

One person on the other forum posted about using garbage can lids for retro bottom drains. The larger the diameter of the drain lid, the less pull around the edge of the drain and less likely to suck in fish..and then can also have a smaller gap. Only thing then to worry about is the lid getting sucked down onto the liner but said to use something non toxic to put under the edge of the rim.

[BruceP]

Mary..... I just wonder if by making a larger diameter lid you would cut down the overall effectiveness of the bd for a given flow. You would have less draw at any given arc of direction .... I think... lol So my question is; would the bd still cover a 6' radius for example or would that be reduced?

[cowiche ponder]

Bruce I had wondered the exact same thing. Not sure it would make a big difference as the larger lids pulls less per inch around the lid, but the lid IS larger so would it affect? Same gph...
I don't know!

[mikeno]

Maybe like this: Bottom drain grid. (http://www.koi-uk.co.uk/koi_farm_page3.htm)

[cowiche ponder]

Mikael that works in that situation because there is not any large stuff blowing into the ponds because they are in covered greenhouses. In a spot where leaves fall into the pond those grids will become a serious problem when they are clogged up by leaves

[bekko]

Face it, when you increase velocity and increase the opening size you also increase the risk of entraining small fish along with the leaves and such. I don't think you can do one without the other. But, your bottom drains should be feeding a sump which is either large enough for sedimentation or convenient enough for easily-cleaned mechanical filtration. Entrained fish should be safe there until they can be returned to the pond.

I would worry about Maurice Cox's grates even in the greenhouse because string algae would easily clog them.

-steve

[cowiche ponder]

Face it, when you increase velocity and increase the opening size you also increase the risk of entraining small fish along with the leaves and such. I don't think you can do one without the other. But, your bottom drains should be feeding a sump which is either large enough for sedimentation or convenient enough for easily-cleaned mechanical filtration. Entrained fish should be safe there until they can be returned to the pond.

I would worry about Maurice Cox's grates even in the greenhouse because string algae would easily clog them.

-steve

Didn't think about string algae Steve as I haven't had that around in awhile, but true for sure.

What do you suggest for a bottom type drain? Someone had suggested larger PVC pipe with holes drilled. I think on Koiphen someone said 1" holes which sounded pretty big to me as it would still manage to suck in a smaller goldie..

I have a 900 or so gallon stock tank I was just looking at today trying to decide how to do the bottom drain for koi or goldies to go in

[bekko]

Air domes help pull debris to the drain. But, the air dome effect only works well in a deep pond. The depth needs to be at least two-thirds the distance from the drain to the wall for it to do its job. So, air domes are sort of a koi thing and have less application in a shallow goldfish pond.

The garbage can lid thing helps a little but is not going to make a huge difference. If the pond drain gravity flows to a sedimentation chamber then I don't see anything wrong with just leaving the end of the drain pipe open without any sort of grate or gizmo.

Your greatest help in moving debris to the drain is going to be the fish themselves. As they root around on the bottom looking for something to eat the debris is stirred (it's called 'bioturbation'). As long as the stuff is kept moving it will eventually find its way to the drain pipe.

If the pond drain is connected directly to a pump then you will have to use a grate or screen small enough to keep out fish and any debris large enough to clog the pump. Routine cleaning of a screen located at the bottom of the pond is a real nuisance. By using a sedimentation chamber between the pond and the pump, the screen which keeps stuff out of the pump can be located in the sedimentation chamber where it is easy to access and clean.

-steve

[Cincy Ranchu]

Steve/Bekko,

Can you look at mu pond blog series and on part 7 or part 8 has the filter pictured, are you suggesting a sediment chamber in line with the pump and screen basket will decrease maintenance?

Thanks Gh

[cowiche ponder]

Steve/Bekko,

Can you look at mu pond blog series and on part 7 or part 8 has the filter pictured, are you suggesting a sediment chamber in line with the pump and screen basket will decrease maintenance?

Thanks Gh

Haven't seen your series, (link?) but do know what Steve is talking about because of my koi pond. The answer is yes. Because all the solids should stay in the sediment chamber. There is a dwell time that is needed in the chamber to allow the sediment to settle out. There is the use of micro screens, prefilters before the pump along with other koi pond technology that can be reduced in size to fit most smaller (most smaller than koi pond) goldie ponds, but are only additions to and not necessary if it's done right.

I have this 900 gallon stock tank and I'm going to play with the filtration on it and see what I can come up with that will work for the koi but also be goldfish friendly so I can use the tank for either one.

[bekko]

Gary, I will study the blog when I have a few minutes.

You want to get out as much of the solid waste as possible before the pond water goes through the pump. The pond environment is good at consolidating waste into particles which are large enough to easily capture and remove. The pump grinds everything up again and reduces particle size. By physically removing solid waste, you do not require your system to digest the solid waste and, thus, lighten the load.

As Mary says, simple sedimentation will remove most of the solid waste if the dwell time is long enough. Most stuff takes about fifteen minutes to settle to the bottom of the chamber. However, with the high turn-over rates being used these days, the sedimentation chamber becomes very large. So, sedimentation is augmented with something like brushes or Japanese matting. The brushes/mat essentially reduce the time and distance a particle must fall before it reaches a solid surface and sticks. But, brushes and mat are more tedious to clean than a simple bare-bottom sedimentation chamber. There are also rotating drums and various other micro-screen units which remove solids in a contraption with a small footprint. They are also fairly easy to clean.

Biological filtration usually comes after solid waste removal and that is followed by water polishing. Depending on the type of biofilter used, the pump will be either after the solids removal or after the biofilter.

Get back to you later.

-steve

[bekko]

Gary,

Putting a sedimentation chamber for solids capture between your pond and your pump is probably difficult because the chamber would have to be gravity fed from the pond and at the same elevation as the pond.

But, your bead filter will capture a lot of that stuff even after it is run through the pump. Bead filters are good at getting out small pieces of debris. They perform best, not immediately after back flushing, but after the beads have captured some stuff and are starting to clog and cake. The more clogged they get, the finer the particle they can capture.

My main beef with bead filters is that they are energy hogs and it takes a lot of horsepower to drive them. As the pore size between beads decreases the back-pressure builds and it takes energy to overcome that back-pressure. The result is less flow for your energy dollar.

Bead filters can be used for both mechanical filtration and biological filtration. However, they can not effectively do both at the same time. When a bead filter is the first unit in line it captures solids. As it clogs with solids nitrifying bacteria cannot function because they are smothered. When a bead filter is placed after some sort of solids capture process, the beads are colonized by nitrifiers and there is good, uniform flow between the beads. How you manage the filter also has an impact. Frequent backflushing decreases the efficiency of solids capture (as noted above) but increases the efficiency of nitrification because the bacteria are not being smothered.

Food for thought.

-steve

[Ichthius]

Hi Steve

There are some very interesting low head bead filter designs. They have no moving parts and are completely gravity fed. Some are even using air chambers for washing the beads so there are no moving parts on the filter itself.