I have some 10' sections of 4" PVC pipe left over from another project that I am thinking of making into fish structures.

My question is if I weight the bottom and cap the top end to leave 1-2' of trapped air(drilled holes & tubing below that) will this provide enough buoyancy to keep it upright?

IME the buoyancy of such "floating" structures changes when plant growth (e.g. FA) occurs on the structure. Then they sink.

You could try securing the bottom end of the pipe to a weighted base (I use leaky 5 gallon buckets) and sink that in place.

Another option is to use an excess of length at the bottom so that it can be driven into the pond bottom with pole driver.

Yes, I was going to use concrete in a bucket or a concrete block to sink it.

That is a thought but I don't want any of it showing above water....especially in the summer when the water level recedes.

The long lasting reliability of trapped air is sketchy, but 1 to 2 foot of air trapped in the top of the PVC pipe should keep it upright given that the rest of the structure is made of plastic tubing that has a specific gravity closer to 1 and not trying to drag it all down. PVC is one of the heavier plastics with a SG of 1.4 so it wants to sink. Most other tubing plastic's SG are much closer to 1 which is what water is. These plastics may float, sink slowly, or merely hover depending on what side of a SG of 1 they fall. With all that mumbo-jumbo said...it would not take much tipping of a rather full bucket base of concrete to take it all down with trapped air being its only means of staying upright. I would suggest forgoing the trapped air and putting some scrap pipe/rebar/angle/whatever (approx 4' long each) through the bottom of the bucket to make and "X" before pouring in the concrete. This "X" will give the whole structure some stability and keep it upright without the trapped air.

Interesting.

Yes

Pics from 2015, and they're still doing their job. 2 bottom floating trees, and the beginning of X frame bottom cover.



Detailed view of how I anchor them. It takes very little anchor weight if the holes are drilled at the correct distance from the top cap. I would drill 18" to 2' down, then redrill another hole above those(if needed) to get the buoyancy correct. The holes for the "limbs" should be loose, or the trees won't sink correctly.

Thanks Al !

[quote=Quarter Acre. I would suggest forgoing the trapped air and putting some scrap pipe/rebar/angle/whatever (approx 4' long each) through the bottom of the bucket to make and "X" before pouring in the concrete. This "X" will give the whole structure some stability and keep it upright without the trapped air.[/quote]

This is exactly what I have done with success.

Some people have found that white color repels fish. Dull dark colors may be preferable

Other threads here on how to but roughing up the pvc will help with detritus growth on the structure which helps with it being effective.

Maybe just a thought...take a old tire and wedge the 5 gallon bucket inside it for more of a floor base to keep from tipping over. Just concrete your pvc into the bucket.

Just remember to drill the sidewalls so the tire will sink.

for ruffing up, I just used my electric hand grinder, even a hand drill with a wire brush attachment will do it also. It's pretty easy. After ruffing it up I added some camo spray paint to cover up the white pipe. The first of the five-gallon buckets of PVC I added I left white and now I never see any fish around those buckets.

Good suggestions.

Jumping in- What is the best artificial structure for itty bitty baby fish? Looking for DIY
Thanks

City dad...I use old Christmas tree artificial garland and trees and wreaths for itty bitty fish. Has worked great for several years. I find it in garage sales a lot and sometimes people just give that junk to you!

Up here, our best option is usually cedar trees. You can cut them almost any size (if they are on your land).

They last several years in the water, but usually get progressively less dense as they degrade. They slowly evolve from "itty bitty baby fish" cover to LMB cover.

When it is time to replace them in the pond, you usually have a new crop of cedars on your land that need to be cleared!

For fry cover I'm shoving plastic plants from Walmart in the bottom in 1-2' of water.. 50$ worth of these provides a LARGE spread of fry habitat.

I decided to turn one of the pipes into a small fish habitat.

What do you think...lay it horizontal next to the walkway in descending water depth starting at ~ 3’ to 7’?

I’m up for suggestions on design and location. Bigger holes?

Tbar, as good as that will work for your itty bitty's it'll be a killer for snagging hooks.

Good point. Maybe I’ll put it under the walkway.

I am no gill net expert, but might that netting trap a fish on occasion? I know my fish trap with 1/2 square wire cloth will occasionally be pulled with a fish half stuck in a hole. It does not happen very often, but something to consider if a better material could be used.

Christmas trees might be a better option. You can stick them under the dock if you like. You could use the netting to make a small fish sanctuary like a blocking net.