Reverse flow returns

[PD100]

Hi

Can somebody give me their views on reverse-flow returns, I can’t quite
Get my mind around the principles involved or the “mechanics” of the
plumbing, any comments/tips greatly appreciated

PD

[netsukekoi]

The only 'reverse flow' returns I have come across have simply been returns which are valved to allow selected returns to be used and for these to swapped in order to reverse the flow of water back into the pond.

My personal view is that whilst nice to have, it is one more potential problem should something go wrong, additional bends in pipework and in a normal well aerated and filtered pond, probably not worth the cost / effort / risk.

Were you thinking of something else?

Martin

[steveW]

Reverse flow returns as i understand it

with the bottom drain being in the middle of the pond, you position the returns so that you cause the water to circulate in one direction (ie clockwise around the drain) this action help the muck to be drawn to the drain.
reverse flow allows you to change this direction to anticlockwise.

normally you would position the returns, for example on a square/rectangular pond, on one wall inthe left side and another in the opposite right corner causing the water to rotate clockwise. using only one return does have the same effect only not as strong. reverse flow would mean you would have to switch to returns in the opposite corners ie bottom right and top left.

it does make the pipework a bit more complicated, but only requires two valves so youcan stop one flow and allow the other.

if you have an irregular shaped pond then it may be of benifit to eliminate dead spots, but cant really see the need. better to put in a deep or mid water return awell as a high return. both in the same area to create the rotation

hope that helps

[PD100]

Thanks Guys

Useful feedback, just about to move from the design phase, to doing
some actual digging, I think you are right in saying the "risk\reward\cost"
ratio is not suffichent to incorporate reverse flow returns into
my pond

If anybody thinks otherwise please post

PD

[Bob Hart]

PD,

There has often been 'chat' about having reverse returns, or even returns where the flow 'sweeps' all the crud towards the bottom drians. To me it's all a load of twaddle. I dont have anything like this and my pond has been running for 16-years. My returns are above the water level and ust splash into the pond, a little free oxygen as well. If you have Koi in a pond and you have bottom drains, you'll find everything goes down the drains anyway. Unless you design the pond real badly, which is unlikely.

My thoughts on returns being near the bottom of the ponds are that you are ust adding pumping head to the pump, as it then has to pump against that pressure.

Others views may differ, but experience shows that it doesnt make any difference at all!!!!

[Gin Rin]

My pond has two (more or less midwater) returns below water, one from the bottom drain and one from the skimmer. The flow around my pond is quite strong, and noticeably so. I was under the impression that a good flow was important and also allowed the Koi to ‘exercise’ and to have something to swim against. Having said that I have also read that Koi get most of their exercise from swimming vertically in a pond, which is another reason I've seen given for the need for a deep pond. Isn't it amazing the different things you read and hear in this hobby trying to sort out the wheat from the chaff is very difficult.

I’ve read the view that reverse flow returns are a good idea as it allows the koi to swim both ways, ie not always clockwise etc, but I can’t see how that is the case as my koi swim both ways and any direction they like for that matter (especially if I come near with a net ) although obviously they don’t have to do so as hard when they swim with the flow. The idea, the promoters of reverse flow say, is that if Koi swim only one direction they develop muscles more on one side, sounds like a marketing ploy to me, an excuse to sell you something because it sounds plausible.

I have seen directional nozzles that allow the flow to be changed using the same pipe work / exit, having problems finding them at the moment though. From memory they were fitted to the ends of the return and would direct the flow by means of the direction they were pointed.

I’ll add the link if I ever find it.

[steveW]

i had one of those adjustable nozzles it came with my Olympic skimmer.
was no use to me as it was designed for a liner and flexible pipe,
not concrete and fibreglass