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Thread: Bottom not clearing
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09-09-2020, 11:11 AM #1
Bottom not clearing
Hi guys
Really struggling with waste on the bottom and draw on the bottom drain. It just doesn’t seem to pull as it should and the bottom collects waste and the drain isn’t doing its job. I have tried stemming the flow of the skimmer line but it doesn’t seem to increase the flow on the bottom drain, the bottom drain pipe is clear as I have use drain cleaning rods until no debris.
I have a 12 inch Avenue hinged bottom drain on 4 inch and a skimmer also on 4 inch. Fed into drum then onto moving bed and a shower pulling around 25k litres per hour across two pumps. Pond is only 3 x 2.4m and I have a mid return pushing around 9000 litres per hour.
The pond is square and I only have the one mid return in one corner and then the shower.
I did try and slope the bottom and finished it with a bed of sand before fitting the box liner but I wonder if the bottom is not flat as I have tried everything else with increasing flow and adding an air ring on top of the bottom drain but still not joy. Possibly the water weight has caused an uneven bottom and debris is sitting in pockets???
I think my last resort will have to be either add an in pond pump and some pipework to create more of a circular flow or empty the pond and remove the liner and board the floor of the pond to ensure a smooth and sloped finish. Neither of which i fancy!
Any other ideas but as usual it is mistakes at the start causing me issues. Thought I had corrected everything this year with updates but as I have been able to feed more due to good quality water this issue has become more apparent.
Sorry for the long post....
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freddyboy Thanked / Liked this Post
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09-09-2020, 11:37 AM #2
Hmmm, annoying.
I had similar issues early on, on a similar sized set up. Usually in the morning but it seems to have sorted itself out.
I think the flow through my skimmer was initially too much (path of least resistance and all that stuff), so tend to leave the valve on my skimmer 3/4 open to ensure the bd gets the lions share of flow. Have you tried reducing the flow to your skimmer over a 24 hour period?
As a quicker test, try closing the skimmer down completely and leaving the air ring on for a couple of hours, then check. That should sort it. Although admittedly not the best for a long term solution.
I find having the air on twice a day really helps sweep solids to the bd - and I have a flat base on the pond rather than sloping. But I dont leave it on all the time as 1) not needed 2) it'll keep fines in suspension and 3) it ruins the aesthetics.
You say stemming the flow on the skimmer does not increase the flow on the bd, but surely it must do? As all the flow has to go through the bd to get to your filters?
Sent from my SM-A520F using TapatalkLast edited by Twhitenosugar; 09-09-2020 at 11:40 AM.
13,000L fibreglassed raised pond with window
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freddyboy Thanked / Liked this Post
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09-09-2020, 11:41 AM #3
It must help but I find then that I have to changed all the flow settings on the pumps as they are running at the max flow of the drum, otherwise I end up with pumps cutting out due to not enough flow.
Will keep playing around with it.
I did have the air on just over night so will try that and reducing the flow on the skimmer slightly and see what that does .
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freddyboy Thanked / Liked this Post
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09-09-2020, 11:45 AM #4
Also my skimmer is on 3" pipe, so if yours is 4" it must be stealing even more flow from the bd than my one is.
So maybe having the valve only 50% open on your skimmer is the way to go.
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freddyboy, gashead paul Thanked / Liked this Post
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09-09-2020, 11:53 AM #5
Ah, even more annoying.
But I still think the issue is probably caused by your skimmer taking too much flow away from your bottom drain.
Although, of course, I could be wrong.
Maybe set your skimmer so the valve is 3/4 open. And as counter intuitive as it may be, then dial back your pumps (I'm guessing they're variable) so it's running optimally with the skimmer not fully open and leave it a week and see if that sorts it?
Worth a try before you start remodelling the pond.
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freddyboy Thanked / Liked this Post
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09-09-2020, 12:07 PM #6
Yes really want to avoid that if possible.
Spent hours at the weekend with an sds drill chipping away at the filter bay floor to get more volume in the moving bed so only managed about 2 inches!
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Twhitenosugar, freddyboy Thanked / Liked this Post
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09-09-2020, 12:09 PM #7
It's never ending isn't it.
And there I was thinking that all the work was done once I'd built the pond.
Sent from my SM-A520F using TapatalkLast edited by Twhitenosugar; 09-09-2020 at 03:25 PM.
13,000L fibreglassed raised pond with window
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freddyboy Thanked / Liked this Post
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09-09-2020, 12:13 PM #8
Agreed, the Mrs thinks I am absolutely mental....then my Thermotec 9kw inverter arrived and she just shook her head
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Twhitenosugar, freddyboy Thanked / Liked this Post
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09-09-2020, 02:23 PM #9
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Twhitenosugar, freddyboy Thanked / Liked this Post
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09-09-2020, 02:55 PM #10
Bottom not clearing
Only thing I can add you say restricting the skimmer does not increase the flow to the bd? Do you mean it still does not have adequate flow to clear the bottom
Last edited by Mikeh83; 09-09-2020 at 03:00 PM.
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freddyboy Thanked / Liked this Post
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09-09-2020, 03:02 PM #11
I have never given it a chance as with no skimmer the flow isn’t enough to run both the moving bed and shower.
I have given the ball valve a quarter turn on the skimmer line, air only overnight and turned down the pumps and will see how I get on and report back.
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freddyboy Thanked / Liked this Post
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09-09-2020, 07:15 PM #12
I’m pretty sure that the 4in bottom drain should be able to cope with 25k. I’m pretty sure I have read others pulling 30k.
So do you have a 10k and 15k pump?
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09-09-2020, 07:19 PM #13
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freddyboy Thanked / Liked this Post
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09-09-2020, 07:22 PM #14
[QUOTE=Mikeh83;350717]I’m pretty sure that the 4in bottom drain should be able to cope with 25k. I’m pretty sure I have read others pulling 30k.
So do you have a 10k and 15k pump?
thats correct if the outlet to drum/sieve lower down the water line the higher the flow rate you will pull from the bottom drain.
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freddyboy Thanked / Liked this Post
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09-09-2020, 07:26 PM #15
Bottom not clearing
So I would say if your BD flow cannot keep up with 25k then there could be an issue in the pipes? Could there be an air lock (not sure how your pipe work is set up)
I use air to clear my floor and it does a good job. I do think smaller but deep ponds seem to suffer more with waste in the floor.
Sent from my iPhone using TapatalkLast edited by Mikeh83; 09-09-2020 at 07:29 PM.
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freddyboy Thanked / Liked this Post
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09-09-2020, 08:10 PM #16
The pond is 1.8m deep so is on the deep side so maybe thats an issue but cannot change that now.
I am running a 20k and 10k vario pumps, will play around with the flows
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09-09-2020, 08:20 PM #17
Not that it's a competition, but mines 2m deep
And I'm pretty sure you're out gunning me on flow. I use an airlift that can shift huge amounts of water, but my drum is a massive bottleneck on flow (Draco Drum Solum 16) and as a result I realistically can only pump about 12- 14k lpk before the drum goes into constant clean mode.
And you have mid-water returns, whereas mine are just below the surface (because of the air lift). So I'm confident tweaking the flow on your skimmer and and tweaking your pumps accordingly should sort it.
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09-09-2020, 08:25 PM #18
I have the solum 25 drum and will keep playing around with it. Cheers
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Twhitenosugar, freddyboy Thanked / Liked this Post
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09-09-2020, 08:48 PM #19
I have a similar issue, rubbish collecting in a corner quite near the bottom drain. I have 2 pumps but at the moment am down to 1. waiting for a replacement that's on a waiting list due to covid shortage. Hoping it will improve with the extra pump.
Another possible cause, the height of the gap under the dome on the drain, if it's to large that will lessen the effective pull, half an inch should do it.
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Twhitenosugar, freddyboy Thanked / Liked this Post
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09-09-2020, 09:11 PM #20
mine s also 6ft deep,
my custom made drum only cleans every hour, can adjust for longer if i want because water level isnt dropping much on the drum 1cm approx drop .
as my drum sit way below the water level i can upgrade the pumps to 2x 20k without effecting the drum as it can handle over 60,000 ltres per hour that will dramatically increase pull on bottom drain and clear the floor.
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freddyboy Thanked / Liked this Post
Best plants to remove Nitrate
pug has a very impressive veg filter on his pond, have a look at some of his his youtube videos....