I'm having a new concrete pond built and wondered if it was necessary to have a wetland. The guy building it is doing a seperate area for this with all the gravel, plants etc so the water passes through all this before returning to the pond. Is this really necessary if I have a settlement chamber and bio filter?
Its going to be a 10 000 liter pond, and I don't want more than 20 fish in it.

Firstly in 10000 ltr. rather plan for no more than 10 Koi.
A wetland is not necessarily a bad idea. Post a drawing of the whole setup including details of the settlement chamber and bio filter for everybody to evaluate.

I have about 30 koi in 8000 liters and I can easily grow them to about 40cm in two years.

Hi Jaco,

Bad advice to a novice!

I am working on an article about new ponds ( New Pond Syndrome), which will explain the matter of overstocking.

Stumble,
Rather start with less then 10 Koi!

Oh I dont plan on starting with that many koi, but will build up to that. This will be my second pond.

I started with pond one, 10 years ago, have since moved so need to start again. I had so many big fish in my first pond, (very overstocked) and although it was stressful to make sure everything was okay, I never had any problems. The pond was in the sun and if the power went off, the fish started stressing pretty quickly. Looking back, I had done so many things wrong.
I dont have pics of this one yet, as it will only start being built next week, but the concerns I have with the wetland, is maintenance and attracting frogs. The pond builder seems to stress that its really necessary as bio filters dont take out the impurities that the plants do. (or so he says)

Another question. My first pond was cement, and we used superlaykhold to waterproof. Although I never had problems and it seemed to work well, I dont see it mentioned anywhere - so is that not the recommended way? [You must be registered and logged in to see this image.] This pond will be cement again, with the rock finish.

Superlaykold is cheap, but there are much better products available. See various discussions on sealers at [You must be registered and logged in to see this link.]

A Veggie filter works very well as an addition to a biofilter, but it all depends on the style of pond, formal/informal, space available and time available. It needs constant maintenance, but works very well in taking out all baddies, it combats algae growth, and can create a natural look and atmosphere and creates oxygen during day time.

However, it can also create a breeding ground for bad bacteria and parasites, it can cause problems with water flow as the plants grow with subsequent stagnant areas, it creates organic matter as dead leaves decay and therefore can put pressure on your biofilter, it can create a problem with frogs and can deplete oxygen during night time.

See also pros and cons of plants under the water plant section of the forum.

Thanks Paul, you've helped me decide on a few things. I don't think I will go the wetland route, too much hassle for me, also I will line the cement shell with black fibreglass. My last pond was huge maintenance, so hope to have a better designed pond this time.
Also I already have seeded filter media, as I have been running a small tank for some weeks now, with a few small koi, so hopefully its started to seed, which I can transfer to my main pond when its ready.