Help with new pond please

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snapper
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Help with new pond please

Post by snapper »

Hi all, first post and sorry its a long one and no doubt this topic as been done to depth. Ok here we go. When I moved house 10 years ago I built a temp pond around 400gal. For various reasons I never built the pond. I now have (and your going to kill me for this) 2 x 10lb plus fish 3 others around the 5-6lb mark and 2 small ones around 14". Anyway this has been haunting me for the last 10 years and something as to be done now!!!

I'm use to groundworks and have a couple of ways off building the new pond which will be 16' x 9' x around the 4' deep mark. Part below and part above ground. 1 x 4" bottom drain (spindrifter) and 1 x surface skimmer to its own filter box. All glass fibered. I need your advice on which way to go. This has got to be spot on first time and I need you help:D

The bottom drain within the concrete base is my main worry. Do I 1: lay the base C35 with fibres and 193 mesh to a depth of 200mm and shutter the outline for the bottom drain and pipework where the 4" pipe will run this will ensure the pipework and bottom drain sit on 200mm of concrete. This will mean digging out deeper for the pipework section but leave a nice deep solid 'grove' with the base to fit the drain and pipework and then fill with concrete.
or
2: as per spec 1 but just concrete in one go over the base and pipework??? My concern is you only appear to have around 2" of concrete over the pipework or am I missing something here :oops:

Whichever way the base is constructed do I then go for
1: laying the dense blocks on their side on the concrete base or shall I
2: do a separate strip foundation nice and deep around 16", build up a couple of blocks and then pour the base inside the blocks and then carry on up???? I'm going to use visqueen as I'm on sand and don't want the water running away too fast from the concrete. Also would you build a pillar halfway along the 16foot run or is this just ott. Render pond all over and bench towards bottom drain.

I hope that all makes sense??

Just one more phewww, filter height, what height do I need the top of the filters to be with regard to the water level, I understand this is very much dependent upon which filters I will be using but at this time I think I'm going for just separate gravity feed filter chambers eg 1 x vortex, 1 x jap matting, one Alfagrog and one air movement bead down to the return pump and separate bypass for the uv from the return pump?????

If you think its all useless tell me and point me in the right direct please, really really need your advice folks.
Manky Sanke
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Re: Help with new pond please

Post by Manky Sanke »

Snapper,

There is a lot of advice on forums about using fibres in concrete bases of ponds. Sometimes as an addition to proper steel mesh reinforcing and sometimes as a replacement. Much of this advice seems to be posters who don't have any extensive experience but are repeating what they've seen on other forum posts. As part of my "Good Water Guide" series in Koi Carp, I covered this extensively in parts 35 to 38. If you contact Koi Carp and ask for back copies, I think the answers to all your questions about construction will be in there.

There is far too much in those issues for me to repeat, or even summarise here, but one important point is don't use fibres in your base. They are unnecessary as an addition to steel mesh and they certainly are not a suitable as a replacement for it. There are many posts that advise using fibres instead of steel but fibres do not add strength to a concrete slab, they are used for a completely different purpose.

Having been in the swimming pool industry since 1984, I can say that the labour costs for the steelwork necessary before pouring concrete are considerable so there is great scope for savings in time and expense. In that time I've seen many companies try to develop cheaper ways to build concrete pools but I don't know of any company that uses fibres instead of steel. This is regardless of the size of the pool, and there is little difference in size, depth or volume between a small "splasher" type swimming pool containing 3,000 gallons and a medium size koi pond.

If that doesn't provide a convincing argument for not using fibres instead of steel, how about a reputable cement and fibre manufacturer stating clearly that their fibres aren't suitable to replace steel?

From their polypropylene fibre concrete datasheet PDF:
http://www.cemex.co.uk/Userfiles/datash ... -fibre.pdf

Under FAQs
Q. Can fibre be used in structural concrete?
A. Yes, but it cannot be used to replace or supplement
structural reinforcement. However, it can be used in
conjunction with the steel to help reduce settlement
cracking over structural reinforcement, particularly
in deep sections such as walls and columns.


Also from the same datasheet in order to make the situation doubly clear (their capitalisation):

NOTES:
1. Effective protection and curing is essential for all concrete slabs - including polypropylene fibre concrete.
2. Polypropylene fibre concrete CANNOT be used as a substitute for structural steel reinforcement.


As to the mesh, you can use A193 mesh but A142 mesh is sufficient and I described other details of slab construction in those parts of my series. As I said above, in those issues, there is too much detail and too many diagrams to reproduce here but the diagram below may help.

The height of the tops of filter bays or other equipment should be fixed so that, with the pumps stopped, the water level in them should be almost at the top. That way when the pump is on, and the water level drops due to pipework friction losses, there will be the greatest leeway before the level is too low for them to function properly.

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snapper
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Re: Help with new pond please

Post by snapper »

Thanks for the time you've taken in a most detailed reply. This is where I am, all dug out, mesh is going in on top of DPM as I'm on sand and don't wont the water to just run through. I'm then having the 2.8 cube C35 pumped to the job. It'll be 8" think. And that's it. I was thinking of using a poker as I've seen these drop the level of 8" concrete by 1" as the air is expelled from the mix but feel its overkill.
snapper
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Re: Help with new pond please

Post by snapper »

THICK even :oops:
Manky Sanke
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Re: Help with new pond please

Post by Manky Sanke »

Snapper,

Whenever concrete is poured it's important to avoid trapped air as far as is possible but, if you can use a vibrating poker, so much the better.
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