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Thread: Nexus auto fault
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01-02-2025, 11:14 PM #1
Nexus auto fault
Came home to 1/3 empty pond the other day.
Nexus is getting stuck mid cycle,
Anyone had this???
Have the waste closed off now and it "reset" after a few power cycles but it's gone into cleaning mode and not come out of it.
Any
Annoying to say the least.
I replaced the auto waste valve last year.
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02-02-2025, 04:15 PM #2
Dunno about fixing it, but you need a float switch on the pump to avoid disasters. They are cheap and easy to install.
2660 Gallons. 4" Bottom Drain and Skimmer. Draco Solum 16 Drum. Anoxic Filtration. Air lift returns.
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02-02-2025, 09:16 PM #3
It's gravity fed .
So she'll dump her guts no matter what !
Went down earlier and it was in cleaning mode but seemed stuck in the washing phase.
I haven't had time to open it and look properly.
I've been thinking about building a new controller for it for a while.
Based on a PLC not mechanical timers but I haven't been arsed......
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03-02-2025, 12:18 PM #4
The auto kit really should have a failsafe design, especially for what they cost.
Its the sole reason I never contemplated having one.
That said, I had 2 near disasters with just the Nexus on its own;
One time where in the height of summer the waste production was so high I was cleaning it twice a day and woke up one morning to it completely empty where it had blocked with waste and the pump had emptied it, overflowed the pond, but the pump was still running dry and red hot. It was after this that I considered an auto kit as that might have avoided this particular problem, but opted against it due to the lack of failsafe.
The 2nd time was after installing a mains fed Drop in Draco. The mains supply pipe had froze so the drum wasn't cleaning, the pump had emptied the Nexus and I had an aqarium heater hanging in the Nexus but because the temperature probe was in the pond the heater stayed on. I arrived just in time to find the Nexus lid smouldering and dripping molten plastic into the nexus.
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Alburglar Thanked / Liked this Post
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03-02-2025, 03:40 PM #5
If gravity fed you need to build in the fail safe. Usually the bottom drain needs to go up, outside the pond high enough, so that whatever happens in the filter house, it could only drain down to the same height of the "up-pipe". Normally a 4" ball valve then a tee on top, to avoid the syphon effect and provide a rodding point for the bottom drain.
...on drums, that's easy to do because the inlets are at the perfect height.
That's the problem with a nexus. They're such a good design until you put an auto kit on. Because you'd really need the inlet to be at the top of the filter. Or actually at least half way up, so you didn't have running height issues in summer.
Then if your valve gets stuck open it's only gonna drain the pond to the height of the filter inlet (if there's a siphon break built in).
For you to build that failsafe in on a nexus you'd need tee off at low level and then run a 90 to the inlet underneath the nexus, then a long up-pipe to over the pond running height. Which would only work on deeper ponds that have a bit of depth below the inlet to the nexus.
... Or you could put a tee on the bottom of the nexus, connecting the bottom drain to nexus inlet, with the redundant hole pointing side ways, then 90 off of that to create the up pipe.
You would loose the rodding facility but wouldn't adversely affect flow from the bottom drain.
Ponding is never as straightforward as you'd think.Last edited by Alburglar; 03-02-2025 at 03:59 PM.
2660 Gallons. 4" Bottom Drain and Skimmer. Draco Solum 16 Drum. Anoxic Filtration. Air lift returns.
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03-02-2025, 04:00 PM #6
....or flog the auto kit and drop in a draco drum, but doesn't sound like that's a perfect solution either, having read Steve's response.
Last edited by Alburglar; 03-02-2025 at 04:03 PM.
2660 Gallons. 4" Bottom Drain and Skimmer. Draco Solum 16 Drum. Anoxic Filtration. Air lift returns.
Filters?
Big Drum, big anoxic filter. Air lift returns. Sit back and enjoy the pond. If it's too late to...