OK, for my next question -- tell me about pre-filters. Are there DIY versions? I know I will need this (poopy turtles), but what kind of set-ups work best with the least amt. of hassle. Will have a bio-filter [undetermined type at this point]. Haven't decided on, or even considered what pump, yet, either. For my purposes, would like a pre-filter that doesn't have to be cleaned out too often (hate to say HOW often since I don't know what's considered the norm, but let's just say I'm somewhat lazy), and one that I'll be able to access & clean easily & quickly.
Mmathis,
I guess I had better ask this question... What is your concept of a "pre-filter"?
Due to the timing of your reply to my post in the other thread, I got the impression that you were referring to a "strainer" for the pump inlet.
However, a "prefilter" to me is a sediment filter upstream from any bio filter or finishing/polishing filters. Whatever they may be. I always think of a prefilter as a very coarse entrapment vessel to capture solids that you don't want to be entrained in your bio-filter system.
If this is what you are referring to, then you definitely need such a prefilter. But, I also recommend some sort of a strainer on the inlet side of the pump, even if it is crude and coarse. I feel that you need something there to prevent sticks, rocks and hard debris from entering the pump impeller. How coarse the strainer is depends upon your pump, the size of fish and the size of the debris that you expect to be in the pond area. If you have NO fish, and little chance of any debris from entering the pump inlet, then you can get by with an extremely open (coarse) strainer filter as a "prefilter for the pump". This will reduce your need to pull that strainer out and clean it often. You may still have to clean it over time, if alga grows heavily on it and begins to restrict it.
I apologize because I was confused as to whether you meant a prefilter for the pump or a prefilter for the bio-filter system.
Going back to your post in the other thread, and regarding the lakescreen filter that I mentioned to you. That lakescreen filter would work excellently as a prefilter or rather as a "strainer" for your pump, something to keeep large, rigid debris like fish, sticks and gravel from entering your pump impeller. But, I would not utilize it as a prefilter for your pond's bio-filter. At least not as it stands off the shelf. It could be utilized to make up a component of that, but not just all by itself.
My hobby of fishing involves using large bait fish (bullheads) which are quite a dirty fish for a tank or pond when in large numbers. Caught from the wild and kept in a tank or pond, they can expel a great deal of waste. This waste has no effect on the pump, but will clog your bio-filtration system quickly and even a sediment filter made from sand or fine gravel would shut down doue to too much bio-waste.
If your turtles (tortoises) are as dirty as my bait fish, you would certainly want a prefilter, but the pump strainer is somewhat up to conjecture. You need one to keep rocks and sticks out for certain, but if there are no fish, you can get by with a pretty large mesh stainer.
What you are doing is quite off the track of what most of the garden and Koi pond folks are doing and requiring. Your situation may be more akin to what I am doing. But, on a much smaller scale and with different critters. Your tortoises won't care so much about the water quality, temperature or pH and hardness, etc. because they don't live in the water. My bait bullheads do live in my pond water, but they are extremely hardy, so they don't care as much as Koi do about the water conditions. However, I am going to have many of them contained in a small area. Therefore, my water is going to foul much more quickly than a Koi pond or garden pond, and therefore, my filtration design is specialized for the type and number of fish that I have and the size of the tank.
May I ask if my logic sensible to you so far?
You and I have a lot of different parameters to be concerned with. Not so much any more than a Koi or garden ponder has, but just different because of the species of animals we are putting in our tanks.
The waste from your tortoises is going to be much dryer and bulkier than the waste from any fish. Therefore, you have a special waste management concern. I have put snapping turtles in my tanks to clean them (the turtles) off and out before I harvest them and they can really foul the water badly and quickly, but they are also in the water all of the time. Your tortoises seem to be just doing their jobs in the water, which is just as bad, I suppose.
Just off the top of my head, a prefilter design for your situation would consist of a small barrel with a settling chamber for the larger solid wastes. Something more akin to a septic tank. In essence, that is exactly what you you are trying to do, dispose of the same type of waste that humans excrete, just on a smaller scale. I would recommend that you Google the designs for septic tanks and search a lot of them. I know that you can utilize such a system for collecting solid wastes in a prefilter before the effluent water goes on to your bio-filtration system.
I wish I knew how to draw this out for you, a picture is better. But, let's see if I can describe it sufficiently, as it is quite simple.
Pump your pond water into the top section of a barrel or a tub of some sort, preferrably HDPE plastic. Let's refer to that as the "vessel" from here on.
If the pump is located in the pond, run PVC tubing from the outlet of the pump to the upper section of the vessel (not into the very top of the vessel or lid, but through the side wall at a level that is about 75-80% of the height of the barrel).
Once the piping enters the vessel, attach a drainage wye fitting with the curved side entry as the inlet and directed downwards. The straight or inline portion of the wye fitting will be positioned vertically so that the water and solids drop downwards and the top portion is open to the atmossphere. Attach a section of PVC tubing that directs the inlet flow towards the bottom of the vessel. Cut that tube off so that it ends at about 10-20% of the total depth of the vessel. On the opposite side of the vessel from the inlet will be your outlet piping.
For the outlet piping, mirror the inlet piping setup. But, position the outlet tube or hole so that it exits the vessel 1" lower than the inlet point.
Next, the tube or pipe that drops down from the drainage wye, cut that off at about 40-50% of the height of the vessel (just a bit higher then bottom of the inlet).
The majority of the solids will either silt to the bottom or float on top, but will not go out your exit piping since it is somewhere in between.
Include a bottom drain if you are able to, otherwise you will have to use a reclaim pump to remove all the solids from the bottom of the vessel at some point in time. When it fills up. This will be your prefilterr solids collection vessel and it will work very well.
Gordy
