Well the first question I would raise is that the bog is going to suck up a ton of water and increase the rate of evaporation. You may need to be constantly adding water as most bog plants can't handle dry soil for very long. Also the water from the root areas needs to be able to drain out or you will get dead areas below the surface without oxygen.

Here is a link that might be useful: Check this link out for Veggie Filters

Another problem you will have is that the pH of a bog is acidic, where the pH of the pond should be much closer to neutral. It might be better to use it for a water garden and just plant water plants in it and leave out the peat for a planting medium you could use gravel. And yes you will have problems with it sucking up water also. Just my opinion.

pikecoe Your respondants are bog purists. Your bog will not suck up water because what your are really talking about is a bog filter. A bog filter is the VERY BEST FILTER you can have.
But the ONLY planting medium you can use is pea gravel and you plant your bog filter with all the regular rooting and floating pond plants. Just make sure you only plant into the pea gravel in the botto of your stock tank and don use any pots or containers. And don't use any fertilizer. Your fish will provided everything you need.
Pump your pond water to your birdbath into the bog and back to the pond. Your bog/filter will work best if it is completley overgrown with whatever plants you decide to use.
Cattails, bog lilies, yellow irises, Bog bean, watercress, papyrus, umbrella palm, pennywort.
I know somebody will start hollering "you can't use that...it will take over...etc etc etc. That's what you want if you want it to look good an be effective. If there gets to be more of something than you want then you remove some and NO.....nothing is going to puncture you STOCK TANK.

Thanks. The link Azponder gave me is basically the same thing, even has a picture of my stock tank. That is what I had in mind. Could you plant lotus in the stock tank with the same effects or do they need to be planted elsewhere in soil? I have a lot of marginals in my big pond that I can thin out and put in the stock tank. Glenda

Anything you plant in there will act as a bio filter. However, be careful of plants that shed a lot of leaves/flowers etc if you don't want to to be slogging around in there to prune them. Some plants do better jobs as filters but which I am not sure. I'd have to bust out my books ;)

Lotus would work fine right in the rocks. Just don't buy anything classified as oxygenators...they should really be classified as SLUDGE.
You don't need to prune anything. A swimming pool net gets leaves out just fine.

Do I need to put some kind of grill or grate under the pea graven leaving a space for sludge or gunk to settle with a bottom drain in the bog filter? Or do I just put in the gravel, plant and maybe just clean everything out once a year. What is best? I don't want to do any more work than is necessary, but I want it to work to full advantage. Thanks for your ideas. Glenda

just plant it and forget it.

That's what I wanted to hear. Thanks. Glenda

ummmm I thought that was what I said?

It might be better to use it for a water garden and just plant water plants in it and leave out the peat for a planting medium you could use gravel.

If you put PLANTS in it and plant them in gravel... that is a vegi filter. Same thing. The thing is sometimes you say Vegi Filter and people flip out and try to make it hard. Don't leave a space, just put some gravel in it (from pea size up to 1 inch) and put your plants in it directly. Run the water from the pond through it. It will work fine. You can do the same thing with a stream filled with gravel or a 5 gallon bucket filled with gravel and a few plants in the top for camoflauge and decoration. Same thing just different ways to accomplish it.

Karen