Ponds and new concrete/cement

Some of you may know I'm re-doing a small pond and I have been reading dire warnings about new concrete or cement work being toxic to fish etc. The pond is for nothing fancy, just a 3 or 4 goldfish and whatever frogs happen to find their way in.

How bad is the problem and if so what's the safest protection/paint/sealant to use?

I'm building a small waterfall about a foot high over the edge of a largish basalt boulder and I need some means of containing the water at the back and either side but I want to keep it all as natural looking as I can.

 

There are several problems when using concrete for a pool.
It should be around 4 inches thick to stop movement, any movement and it will crack, you can during construction press in chicken wire to act a reinforcement .

You should also make it with sloping sides so that if the water freezes as it expands it rides up the sides, it has been known for thick ice to split concrete pools.

To seal it I suggest a sealer such as G4. You should apply 2 coats, allowing it to dry between each coat. The first coat should be applied left to right only. The second coat should be applied top to bottom only. In this way there should be no where that has not been sealed

 

Hi frogesque,
here is some advice about pond-sealants. Good luck!


http://www.lifeforceonline.co.uk/pond_sealants.html

 

Thanks for the help

The pond will be constructed with sand, underlay and poly pond liner. I would have liked to use Swedish butyl but the cost is prohibitive. I did think about a concrete pond but think it's far too much work to do for one person mixing with shovel and barrow.

To seal the waterfall I'll take the liner underneath the boulder (sand bed, rubber car mat, liner, rubber car mat, boulder sandwich) and cement stones in place to reinforce the outside and have 'dry' stones inside to hide the liner and hold it in place.

Very interested in the black Aquaseal mastic. I have a feeling this could be usefull for the underside of any overhanging edge slabs.

Biggest problem I have at the moment is the hole keeps filling up with water due to all the rain. Last time I emptied it there were about half a dozen year old baby frogs and I expect they are back in there again :D There are also big mummy and daddy frogs lurking about and they were starting to croak the other evening (no frogspawn yet though)

 

If you can use one whole liner including waterfall.
If you can't don't forget to put the waterfall liner OVER the pond liner, quite often people put it under for neatness.

 

When we did our pond we were told to fill it first with a solution of potassium permanginate, I think to neutralise the lime in the cement, leave for 24 hours then empty and re-fill. Luckily it's a small pond so was easy to do, this was 14 years ago and have had no problems since.

 

I managed to get a complete liner and the pond was filled today. Despite being a bid of a mud wallow getting the hole sand faced then installing two layers of Geotex membrane underlay it went in OK then finally the liner was added.

Just in time as there there were a couple of amourous frogs already in the flooded hole so they were carefully fished out, put in a large bin and re-introduce to their new home. Throughout it all there was no way Mr. Frog was going to let go of his lady love :D There was also an asssortment of other pond creatures, baby frogs, a bit of sludge and some of the old plants introduced just to give it a kick start.

The water is a bit cloudy and I haven't made the filter yet so there's still a lot of work to do but at least the little waterfall is working which will add oygen and clear any chlorine and as it's totally enclosed there should be no need for any cement work within the water membrane.

[ 06. March 2007, 12:31 PM: Message edited by: frogesque ]