My new pond is 4.3 x 2.5 x 1.5.
One or two bottom drains? builder seems to think one, but I say two.
He says flow rate will be slower with 2 drains, and some sediment may sit in the pipes. Its a gravity fed system. Pump will be .75kw

please help.

would do two, once built you can not change from one to two....

Put two in. You can always "plug" one of them to get stuff out of the pipe

That wasmy thinking too, to add o later on mayor headache!

The normal rule is 1 bottom drain or skimmer for every 10 000l - 15 000l of water.

Im impressed with your builder, showes that he knows what he is doing.

If you put in 2 bottom drains in then you should generally have 2 seperate pump and filter systems not one, otherwise the flow will be too slow if its all running from 1 pump.

This is usually where people make the mistake, they put in 4 BD that in theory 4 x 15000l of water per hour but then somewhere along the line they connect them all to the same 110mm or even 50mm pipe. When you do that you reduce the flow down to 15000l from all 4 BD combined.

Also remember that water takes the shortest route...so if you have 2 BD and one settlement chamber and a 0.75w pump doing 21 000l/h then you will get your max flow from the BD closest to the settlemnt chamber and the remainder from the other BD. So if i may theorise here... you will get 15 000l from one BD and 7 000l from the other but this will no be exactly true as you will loose waterflow from the BD for every meter of pipe and bend in the pipework.

So a seperate system for every bottom drain is generaly the rule....You might be able to get away with it because you are running a 0.75 pump.

By installing x2 BD's with 110mm pipes not conected to one, will give you plenty of options for future changes and add ons as your needs for a better system grows. Installing a skimmer will give you an 3rd option for 3 independent suction lines on your pond. With a gravity fed plan you will always be able to change as budged becomes available.

To save on cost you can add a gravity fed standpipe settlement chamber for the 2 BD's and draw water from the settlement using a number of filtering options including a SF. I know keepers will disagree, take a look the pictures of my very small standpipe settlement chamber and the sludge that collects in this chamber before is passes via any filtration, therefore lessening the load on my filters. I know its hard to believe for some but very clear water is possible..

I agree with Bobby. Sounds like a great idea. My QT pond is based on that theory and it is so easy to clean and a great pleasure to watch

as bobby and wayne said.

Each BD must lead to settlement or its own pump.
Pointless connecting them.

I personnally prefer the settlement chamber route.

Stand pipe into bd where it comes in at the bottom of the settlemen, drain chamber, pull stand pipe and flush reapeat with other pipe.

simple and easy

Thanks for the replies, some great points were brought up.

The BD will run to the the settlement chamber - has 3 sections, I think the first chamber is empty, 2nd has brushes, and will have to take a look at third?? I forgot about that one- I suffer from CRC syndrome. (can't remember crap)
From there it goes to the bubble bead, then huge bio filter, with several returns to the pond. (the 55 UW will be on one of them) I will also have a feed going to a water feature. I want to add a trickle tower later which will run from its own submersible pump. If each BD needs its own system and pump, it seems pointless me having them, as i dont want to run too many pumps etc. He is also installing a skimmer.

I doubt I will ever extend this pond, as its built on a bank, with limited space to extend, with the whole one wall exposed. (out the ground) Thats a really expensive way of doing it, but that is where I wanted it.

I am not explaining myself very well, when I mentioned add-on it refers to the filter system not the pond. You do not require a pump for every BD via a settlement chamber. A 12000lt waterfall pumps will use less electricity than one speck pump (160w) each. It is more expensive initially but saves money long term. My complete systems operates and run 3 lines with these pumps. My Nexus work very effective with a 12000l waterfall pump pushing water to a 50mm mid-water inlet pipe and 4x 32mm overhead waterfall pipes. I am not trying to tell anyone what to do, I am only providing alternative options for a gravity fed system, I change my first filtration system about 6 times to find a happy medium. The options on a gravity-fed system when planned properly is endless.

The first empty chamber is 100% to host both BD's and a 110mm drain/purge pipe. I am sure you are aware that chamber 2 and 3 must also have a at least a 50mm drain/purge pipe.

Hi,
You need to put the breaks on this project until you have it figured out. Remember the saying - build a pond incorrectly once and you will have a life time to regret it.

With all due respect - the way some builders do pipe work on ponds leaves a lot to be desired.

110 mm pipes can get around 14,500 liters per hour through them when gravity fed. There are lots of things around gravity fed pipes such as friction losses with different materials bends etc. but lets work on 14,500 liters per hour.

Your ,75 Kw pump draws and pumps about 25 - 27000 litres per hour. Depending on the pump some will only pump around 23,000 liters per hour.

Your pond volume is about 16,000 liters.

One pump will do everything you want on your pond and will have a very good turnover rate which is critical to the success of the project. You and the builder just need a little brain work to figure it out BEFORE you start cutting and glueing piping.

Two independant 110 pipes from the bottom drains to a single discharge box is the way to go. ALL FITTING MUST BE GLUED - is the builder aware of this. These are not sewage pipes but pipes under pressure at th ebottom of the pond.

Is the builder aware how to seal pipes in the discharge box?

Your discharge box collects the water and you should have another pipe in there to completely flush this area when necessary. Moving the water to your second and third chamber - which seem to be mechanical filters is good - keep the way they are connected as open as possible. i.e. two two three 110mm pipes (if you are using pipes.)

Any piping restriction between any of the components of the filters will limit the flow rate and destroy any calculations you have made. Also you may find the ,75kW pump sucking a chamber or two dry because of the restrictions.

Any of the chambers must be designed in such a way as to be able to drain the water out of them so you can clean them from time to time.

Use 63mm piping to the pump and from the pump where ever possible. Limit the number of 90 degree bends. If you gravity feed through the first chambers you get to the pump. Then the system after this is under pressure. Your bead filter etc has the water pushed through it. So to your UV lights. The out lets from these things can be directed anywhere - to your trickle filter, to your water fall, back to the pond etc.

Your surface skimmer is very important to keep the water clear. Make sure the builder leaves the floating gate inside the skimmer - if you are using a swimming pool skimmer on the pond. This floats up and down accoriding to the level of the water and causes a thin film of water to pass over it - this thin film of water skims the surface. Having an open pipe at the edge of the pond does not work as a surface skimmer. You can take a 50m pipe from the surface skimmer directly to the pump and place a 50mm valve on it to control the amount of water from the skimmer.

One further thing - how the chambers are packed. Ask the builder.

One more thing - the "huge biofiler" - what is this and what is inside it?

A diagram of how this is going to work would be much easier to analyse and see what is going on.

Regards,
Chris

Thanks for the help guys - I really appreciate the input!
Sorry Bobby, I misunderstood you.
Chris, my pond builder is experienced and yes, does glue all the pipes, and was recommended to me by a landscaper who always uses him for the koi ponds. He also is a koi keeper himself, and has built many many really nice koi ponds all over.
Here is a pic of the settlement chamber. it has dividers with holes cut out all the way down i think.

The surface skimmer he is using does have a flap. I'm still a bit concerned about the fish getting stuck in there as I never had that on my first pond and hear stories of this happening..

I will have to get a diagram of the setup. I know he has worked out all the returns etc, so that there is a nice water movement around with the BD in the middle. Oh also - the SC and Bio do have drain pipes if i want to clean them.

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I agree with Chris, and I would insist the builder use the epoxy product Prostruct 67ns to seal all pipework in the sement. You need to sand the PVC pipe slightly and prostruck will do the rest. It sets harder than concrete I even used it to fix a sagging overhanging brick column. Thanks to Oooom Pieters wisdom!!!

I see most keepers use ordinary 110mm toilet pvc pipe to save on cost for a bottom drain.I my opinion this is insane to save on a decent class 6 pvc 110mm pipe, considering its under all the concrete in the lowest point in the pond. When this gets damaged it cannot be reached without braking concrete. For plumbing purposed under ground its not a problem. I damaged my house 110mm sewerage pipe twice when I was doing my pond build, its not designed to handle this kind of weight and pressure .

Bobby, the pond builder didnt make this SC. Its a bought one.

Hi Stumble, just a note on the skimmer. Skimmers are suppose to skim the water. So when installing it try and calculate the water level so that you only have 1inch of water entering the skimmer....that way no fish will swim in either. I did not calculate mine properly and now have to use a brick to adjust the level of water entering the skimmer. If your skimmer is too submerged then it does not removed the dust or objects from the surface as it is then sucking water from below the surface.

I dont recongnise the pipe make so am not sure but it looks like normal yellow "waste pipe" to me. I used 110ml class 12 for the 2-3 meters of pipe that runs underneath my pond. I did that cause they pipes are running at 3m below surface, thats alot of pressure on it. The rest of the piping that is not under the concrete, the piece that comes up to the surface is class 9.

I see your bottom drains dont take air, are you going to modify them to work as diffusers?

Thanks for that about the skimmer Wayneb. Thats a very good point. I can check up on that. I'm so glad you pointed it out before it was set. I'm sure my builder knows about that, but I like to also be aware so I can make sure its done correctly.
I wondered why people kept saying their fish got stuck on their skimmers, but makes sense what you say.
When you say the BD 'dont take air' ?? not sure what you mean. Are they supposed to? Dont know about the diffuser - ?

So far the foundation and floor slab has been thrown all in one. Floor is about 15cm thick with crushed stone and cement mix.

Hi Stumble, judging by its colour it's a normal toilet pipe, the correct one as Wayne said class 12 is a dark blue pipe with a very thick wall. The glue in the picture is PVC weld to join the PVC pipes and will not replace a sealer like prostruct 67ns around the piping and the cement were it enters the pond. I sealed mine before and after plastering with this product. I notice a toilet type fitting on your bottom drain, here I personally will only use high pressure PVC fittings normally dark gray in colour. I am sorry but the wire mesch in the background is extremely thin, if intended for the slab, I would recommend y8 or y10 steel mesch only, for the purpose of binding the floor slab.

I do not mind to shut up, in my view the material you are currently using will increase the risk of a problem and is not worth the difference in cost.

stumble wrote:

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When you say the BD 'dont take air' ?? not sure what you mean. Are they supposed to? Dont know about the diffuser - ?

I see your post now, if the slab and BD has been done, you have missed the boat on the diffuser, you should look at other alternatives to get increased aeration into the pond. Slab could work but a bit on the thin side in my opinion for 16000l of water.

Yes I see that fitting on the bottom drain, but thats how you buy it. (its already attached) I see this box of fitting that he is using.
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Also forgot to mention, slab is on solid rock. They were breaking out rock for 2 days with jackhammer, and was happy of the rock floor - and couldnt go any deeper than 1.5 because of the rock.

Aah, this is more like it!

Retrofitting a bottom drain to a diffusser bottom drain

Note, this is how i did mine originally. I have since found a beter way.

The mesh that you are using can work if you add 1 layer or two of it into the floor. Stacking it in otherwords.

The class 12 pipe has a wall that looks 1cm thick. Its rather expensive so i only used it on the parts below the concrete upto the first join.

Thanks Wayne. Guess as Bobby said, I missed the boat on this one.
I've never seen that done.

So com'n give us a sneak peak at the pond.

I'm on my way out now, but have a pic of before they started - this is the area. on the right hand side, right up against the verandah, to the right of the small palm tree, with a bit of vegetation removed.

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The last box of fittings is the real deal Stumble, a very nice setting for a Koi pond. You must show us some pics as you go along with the build.
For info, Willpet sells the BD's already fitted with nessesary connections and diffuser. Only the best with the build, to get builders not to take short cuts and to complete as per quote, is a mean challenge on its own.