CATCH BASIN

[Mmathis]

I've seen this mentioned in several posts and was curious about how to make one. Are there any pro's & cons?

 

[addy1]

I have catch basins in my streams, to me they are depressions that collect water and keep it there even if the stream is off.

 

[Waterbug]

They're placed under waterfalls.

Trap DOC foam, creates current on the pond floor, keeps the surface still for better viewing of fish.

 

[Mmathis]

Waterbug, how do you construct a catch basin under the waterfall? Since all we have now is a hole, no liner yet, figure this is the perfect time to "build" it into the plans.

Would it be something you could start out with before you lay the liner? Or is it totally something to construct after-the-fact? Since I notice in your drawing [your drawings are very helpful, BTW] that there is a gap to allow the water to flow out from the bottom, wondering how to accomplish this....

 

[sissy]

Have to ask finally if you have a catch basin and you are wanting the water fall to aerate the pond wouldn't the catch basin stop that from happening .I did this so I would still get the water aeration in my pond

 

[Mmathis]

Sissy, good question! I like the idea of a catch basin, but ... Anyone with input?

BTW, Sissy, I LOVE your turtle spitter! Have seen one both at LOWES & HOME DEPOT, so guess I better get mine before they're sold out for the season!

 

[sissy]

I got mine at ollies and all the ones I bought were either 3 or 5 dollars for the larger ones last year .I love to go to ollies to find the bargains .They had shelves full of them last year .

 

[Waterbug]

Waterbug, how do you construct a catch basin under the waterfall?

I build them after the liner is layed, on top of the liner. You can make sure there is a flat spot under the liner. You could cut the soil back if you wanted so the whole basin was more into the bank than out in the pond.

On top of the liner I put a bed of mortar and set concrete block on top of the mortar in the general shape. This all very free hand, I don't even use a level. I do kind of step it back a bit so it leans into the pond side.

I let the first course set up for an hour before laying more courses, or over night. Then stack up additional blocks with no mortar, called dry stacked. I keep the top of the blocks below what will be the water level.

There will be a lot of gaps between the blocks and liner side. I stick broken block pieces, bricks, rocks, what ever, in holes with some mortar. Nothing fancy.

Then fill the holes in the blocks with concrete, not mortar. You can also fill the blocks as each course is laid. That can reduce concrete flowing out of holes. You do keep the concrete very firm, like you can form it into snowballs and they'll keep their shape. When put into the block holes you use a stick, like a 1"x1" to pack down the concrete.

Then mortar rocks on top of the blocks to end up above the water line and the look you want.

...there is a gap to allow the water to flow out from the bottom, wondering how to accomplish this....

Can just be a gap left in between blocks, or a single block laid on it's side so the holes. I like a short length of 4" plastic drain pipe, but that's only because I always have some handy.

 

[Waterbug]

Have to ask finally if you have a catch basin and you are wanting the water fall to aerate the pond wouldn't the catch basin stop that from happening .I did this so I would still get the water aeration in my pond

The catch basin would increase O2.

Most people think there's something about the action of a waterfalls that adds O2 but really it's purely a water movement thing. Anything that mixes the water increases O2. For example many people think the bubbles put out by an air pump are what puts O2 into water. But really it's only that the bubbles moves low O2 water from the bottom to the top. The finer the bubbles the more water will be moved. It just happens that an air pump is more efficient at moving water this way than a water pump.

And even if one wants to believe that water hitting the surface is what adds O2 the falls still hits the water in exactly the same way with or without a basin. You get the exact same sound. The only difference is water is directed to the bottom.

The added bottom movement increases decomposition of waste. The basin acts as protein skimmer reducing DOC levels. So these things would also increase O2 levels longer term.

Gas exchange details...
Gas change happens at the surface. O2 wants to spread from the air into water that is low in O2. Same reason why gas spreads out in a room. But the O2 has a harder time spreading in water. So in perfectly still water only the thinnest layer at the surface would gain O2. As water is moved the surface O2 rich water moves around the pond and new O2 poor water comes close to the surface and picks up O2. On and on. Exactly the same way our blood comes close to air in our lungs and gas exchange happens. The more movement the more the total water column stays at maximum O2. The faster your heart pumps blood the more your blood stays at maximum O2. Other gases exchange the same way.

So water coming down a stream and falls is probably at max O2. If it hits the surface and spreads out the water at the bottom may stay kind of still and low O2. The basin sends that high O2 water to the bottom and pushes low O2 water to the surface.

In high fish load systems you won't see any water falls or fountains. You will see a lot of water movement, You will also see air pumps, but again, just to move water as cheaply as possible.

 

[sissy]

ok then if you had a water pump just about at the bottom of your pond and moving the water then it will put out the same amount of 02 as an aerator if it was moving the water around .I remember I had a pump in the water that had one of those foaming heads on it and 1 of the fish had knocked it off the basket i had it wired too and when i got back after being gone 10 days I noticed my filters were really dirty and the pond was extremely clean and clear .I guess it really pushed what was off the bottom up .I use a pump in the winter with a hose and pvc pipe that has holes drilled in it and an end cap and all winter ,even this past winter water was clearer than normal .I always stand it up in the pond and wire it to the bridge .

 

[taherrmann4]

I am like addy where I have one catch basin in the stream. Did not want one in the main pond, wanted to keep it looking more natural.

 

[addy1]

My waterfall, bog and steam are in the 5 foot deep area. To build something like wb's drawing would be difficult and not look right for my pond. Don't really need it, have no foam issues and plenty of aeration.

But if you have foam it would help

 

[Waterbug]

Addy's pond will of course never have foam. But most ponds will eventually at some point for some period of time. Sometimes just for a few weeks, sometimes for months. When it does appear most people seem pretty unhappy.

 

[Mmathis]

This might seem like a dumb question, but if the surface water has less motion, will that make it more likely you'll have a mosquito problem?

 

[addy1]

This might seem like a dumb question, but if the surface water has less motion, will that make it more likely you'll have a mosquito problem?

Not with fish in the pond, they snack on them.