Bottom drains 1 1/2 - 2" - 3" or 4" flow rating [gph] ?

[whiskey]

hi all, never had or fitted a bottom drain, so wanting advice from all. In spring next year doing up grade to pond , starting by digging deeper laying bottom drain [gravity feed] to go to sieve pumped to waterfall.
Question i pose would it be better to fit 4" bd and 4" pipework now ,if flow is too great, could it be controled by stop/gate valve and finally what flow rate would 1 1/2", 2" , 3" , 4" pipe work [gph] produce.
Is it worth fitting one with aerated unit.

 

[fishin4cars]

from what I have gathered in my quest of information is that 4" is best. This will help the most in preventing possible clogging in the pipe work. I'm under the impression that the bottom drain goes to a pit, the flow rate is determined by the return flow so really no need for a gate vale or flow restriction as you control that by pump pressure/return flow rate. Again, this is new to me as well. PLEASE post pics if you get a head start on me! I'm following a few threads on a few forums on different applications I'm interested in. even went to a pond builder today to get a quote on having it professionally done, although I'm planning in going into business on my own installing ponds I would like a little more experiece in this type of pond build before I start putting my name out there. water gardens I'm pretty comfortable with, true Koi pond/fish only pond with advanced filters/BD's, Not so much.

 

[fishin4cars]

BTW, whiskey, be sure and check out some of the many youtube video's on BD's and areation, I would recommend air assist top, can't go wrong having it and not needing it, could be a PITA to change out if you find you don't have it and do need it, Price isn't that far apart in my opinion to get one that has air assist built in, Plus with air assist, not only are you pulling more waste toward the drain but your increasing the saturated O2 level as well.

 

[koiguy1969]

aerated BDs are more efficient because the air creates an upflow of water that travels up in the bubbles, spreads out at the waters surface, and is drawn back down along pond walls. this light, but moving water current helps move debris down to the drain to be sucked in.

 

[Waterbug]

As Larkin already said, 4". And also that the flow in a gravity return drain is exactly whatever the pump is putting into the pond. So you just need a knife valve in case you have to swap out equipment someday.

Keep in mind that the air flow drains are only one part of what's needed to create current to flush debris to the drain. You also need "tangential pond returns", a name I recently learned.

Be sure not to have any vertical bows in the pipe run. Air gets trapped in there and water won't flow as expected.

 

[whiskey]

Hey cheers guys , on my wife computer as mine......fails to start ....YET AGAIN....errrrrrrrr. goes in tomorrow, so will lost for one week with out it.
Thanks for all advice. really plannimg changes in a couple of months ,bigger, deeper, with bottom/side drains, my own filters and my own tower..going to be fun,fun, fun next year.
Got blocks coming next week, before price increase in january.

 

[whiskey]

hi all just about getting my head around every thing being on the level which is strange when im use to pumping first. Just finished skimmer to waterbug design, will brick it in , when i start blockwork.

 

[whiskey]

hi guys need advice on design ..if sieve intake/filler is 4" and the drop chamber is greater .lets say , 8-12", would water level lower to make sieve work normally. i know the sludge drain would have to have a stop valve to stop water loss before start up....SO WOULD IT WORK. cheers

 

[Waterbug]

I'm not entirely sure I follow the question. The water level in the "drop chamber" (good term, did you coin that?) does drop when the pump is turned on. The difference has to do with the amount of water consumed in pipes and to fill the pond enough to overflow the sieve.

Is this a DIY project or purchased sieve?

 

[whiskey]

hi waterbug yes this is a diy filter . Can think of many ways to use sieve using pump first, but trying to get my head around gravity first. Could gravity to sieve then pump up to filters, just trying to understand my limited options.
Would like to make it as drawing with extra chambers for filter media but my concerns are with the sieve action or draw of water from the pump to lower water in "drop chamber", guess its down to trail and error on pump size and "drop chamber" size .....but i feel it should work what are your views

 

[Waterbug]

Yes, you've have it. The manufactured sieves and some of the DIY versions use a floating weir to make sure the pump gets enough water. When the pump is turned on water level in the drop chamber falls along with the weir float, weir lowers letting in more water. However, from what I've read, the DIY floating weir is difficult to get right. My DIY experience makes me not to even want to try it if there's another choice, and there is.

The answer I think is exactly what you said, the size of the drop chamber. I don't know if you've ever had interconnected ponds, or maybe a better term is interconnected pools forming a single pond. The lowest pool has the pump which pumps into the highest pool which overflows into the next lower pool and so on and so on until the water gets back to the lowest pool. When the pump is turned on there is a delay until you see water overflowing into that last pool. During that time the pump's pool gets lower and lower. That pool must be able to hold enough water.

To me the drop chamber is that lowest pool.

If the drop chamber is large enough no floating weir is needed. A fixed weir can be used and that's super easy and super reliable. And really that's the only complicated part on these.

So the question is how big should the drop chamber be? I think the best that can be done is an estimate. Part of it is how much water the pump puts out. Water only travels so fast, so higher rate pump will pile more water in those other pools than a small pump. The other issue is surface tension. The level in each pool has be raised higher than it's overflow weir. I guess at that and say 1/8". For the pump I add another 1/8" for say a 1000 gph pump, 1/4" for a 2000 gph, etc.. Then use the online volume calculators using the dimensions of all pools and streams times the surface tension height guess to estimate the lowest pool size. That kind of gets me the minimum.

Once I have an idea of the minimum I can start to think of ways to integrate that low pool into the design. For example, if a gravel filter is wanted I can use the low pool as a gravel filter. Now I can double, triple, etc., the size of that low pool and not be "wasting" resources or space and am pretty sure my drop chamber is going to be plenty large enough. Another design choice is to place a deck over the low pool so I can make it larger and not waste space.

But I like gravel filters. They can be any shape, hold plants, great at killing unicell algae, etc.

Couple more issues for the low pool (drop chamber). The larger the gravel filter the less the water will drop in it. If too small, or real deep and narrow, the water level can drop below the roots of plants (if any). Two ways to deal with this.

1. Make the gravel filter shallow. Same volume, so the filter would need more square footage. I think a 12" to 18" deep gravel filter is best anyways.

2. Put a refill float valve in that low pool. The level will go down when the pump turns on and the valve will start adding water until the gravel filter is back up to a constant level. This will also keep your pond topped up.

2a. Refilling the gravel filter means that when the pump is turned off that low pool is going to overflow as the "piles" of water in the other pools drain. So I think putting an overflow pipe in that pool is a good idea so you can control where that water goes.

Note that all this complexity for that low pool is true for any interconnected pool pond system regardless whether a sieve is there or not. I personally like interconnected pools, I like the look of a constant water level, the look of ponds filled to the rim. So for me a sieve doesn't add much complexity or expense. For others that may not be true.

The pump in the low pond generally goes to the filters. Trying to integrate filters into the gravity flow after the sieve is pretty tricky and I don't see the need for that. The sieve's job is to just keep feces out of the pump.

Make sense?

 

[Waterbug]

When using the sieve to remove feces the "fixed weir" before the sieve is actually the pipe from the bottom drain. It overflows like a weir so weir wasn't the right term really.

A sieve can be used after a skimmer to remove floating feces and other stuff. Less cleaning the skimmer basket.

 

[minnowman]

Whiskey, If the wall to the right of the foam filter tank is at the same elevation as the wall before the sieve, water will back up until it flows down the waste drain at the sieve. To solve this problem, the pump should be in the drop tank and that tank has to be large enough to allow for water level drop due to leakage or evaporation. The biofilter area should be after the pump as Waterbug suggested. The flow rate through the biofilter will vary too much to use gravity flow before the pump. With that arrangement the water level in the pond will remain constant.

 

[CliffandJoann]

Hi Whisky, we have a BD gravity fed sysyem. our BD is 3" but we recommend 4"
The second year we added a 200 gallon biological pond to our system. Our pond water
goes through three outside tubs then travels underground to the bio pond, goes through
the bio pond and then exits the bio pond travels back underground and re-enters the
pond and the cycle starts all over again.

this is the layout

this is a couple of drawings, one with just the pond and filters...
and the next one with the bio pond

the pond also has 'rocked' shelves all around (except where the beach is)
even the big waterfall has 'shelves' rocked up to the ground.

this is the actual footprint in the snow...note the bio pond in the back -- located
about 18 feet way on the upper right.

this is the pond operation details...

The DYI mechanical filteration system works as follows: ​

The mechanical filters consist of three 35 to 45 gallon rubber maid type tubs, daisy chained together.​

The first tub:In the first tub is standardfilter material to catch the heavy stuff. This filter material is several individual pieces of filter material rolled up and packed in between dividers (At one time we used to use Dacron batting, but found it difficult to clean.) The clarity of our water determines the frequency of cleaning the filter material in this first tub. The cleaning ranges from every day in early spring (due to the tannins from the large oak trees we have) to once or twice a week, later in the season. The clarity of our water governs this task. Most of the fish waste gets caught in the first tub.​

The second tub:The second tub is again divided into three seperate compartments. We cut the sides off of plastic crates and made three plastic sleeve. Each sleeve is wrapped one time with standard type filter material that we purchased at the pond store. This filter material is specifically for mechenical filteration and every pond supply store has it. This standard filter material is much easier to clean than the Dacron batting. These wrapped sleeves are standing upright in the tubs and are cleaned usually one to two times per week, again depending on the clarity of our water. ​

The third tub: The third tub houses the five pumps and behind the pumps is a fine mesh pad that we purchased in an equiptment rental store for 10.00 dollars. (It is the pad that is placed lastly on a floor sander to finish the job. ) This pad is cleaned one to two times a week. Whatever makes it through the first two tubs gets finally caught in this last pad. We call the last tub "the polishing tub' as it gives the water it's final 'polishing' before exiting and making the journey to the biological pond, which does the final scrubbing of the water before reentering the main pond again...Again the clarity of the water as well as the water flow in the last tub governs the frequency of cleaning. As soon as we see the water flow slow up in this last tub, we know the filter materials are getting clogged and need to be cleaned.​

The beauty of this system is... as your pond and fish grow--so can your mechenical filteration system--just daisy chain another tub on. We started out with two tubs and as our pond grew and our Koi grew we added two more.​

We have a lot of large koi and as you know Koi make a lot of waste. The maintenance routine I have described is our usual routine. Our pond is always clear, the clarity of our water always ranges from clear to cystal clear to gin clear. ​

We attribute the health and clarity of our pond to two things, Firstly--The frequent water changes that are done each week by adding fresh water each day for ten to fifteen minutes, thus resulting in a 35 to 45 % water change over a one week period. We never partially empty our pond and do a large water change at one time. ​

Secondly--The frequency in which are filters are cleaned. If you want to maintain a clean and healthy pond with cystal clear water, you have to keep on top of cleaning the filter pads.​

Biological Pond review...​

The biological pond is located 18 feet from the main pond it is a 200 gallon​

pond filled with plants and zeolite rocks. The water leaves the last filter box and travels underground to the bio pond, travels through the bio pond getting scrubbed by all the vegetation, then exits the bio pond and travel back underground and re-enters the pond from under a small wood dock​

in back of the main pond. We added the biological pond in 1998.​

Note, We never vacuum our pond or had to vacuum our pond. Our pond is bare bottom with the exception of our two pebbled beaches. During our daily water additions, we sometimes lay the water hose on the bottom of the pond to sweep all the mulm toward and into the bottom drain. We clean our beaches and shelves the same way, by using the hose to release the muck and mulm that gathers around and between the rocks. In the beaches we swish the rocks around and turn them over to release any waste or fish food that gathers in between and under the rocks.​

No UV Light and No Chemicals...We also do not use any chemicals or use a uv light. There is no need for it, as our pond is always clear, we maintain clear healthy water with frequent water changes and keeping the filters clean. We believe the uv light also kills the good bacteria.​

This is the dock...​

the little dock has many uses, the flows back from the bio pond from under​

this dock, it also houses the DIY skimmer that is only in use in early spring​

when the tannins are falling from the trees. The rest of the time the skimmer​

is not necessary as the BD and filter system work so well​

​

The dock has many uses...​

​

 

[minnowman]

Joann, Thanks for posting your pond and filter layout. Your results speak for themselves. Beautiful water.