Fair comment but thats a big job (ie not something I can do in 10 minutes) and worst case, all it will do is prove my Nexus is different to the way it should be (and at 4-5 years old, it is not going to get changed or fixed by EA). (Plus I don't think that is the case - the level on both sides is quite low)
I'll live with the lower flow (I always thought a slower flow through a Nexus was more efficient anyway) - especially as the bigger pull will be through my sieve/bakki - so I'd prefer debris to go that route leaving the Nexus to do fines and biological stuff...
Thanks (& when it stops raining I'll check my skimmer and let you know)
Michaelb wrote:
The only thing I have possibly done different to others with this installation is that I ran 4" pipe from the nexus right to the inlet of the Optimax ! using the 4" fitting that comes with the pump.
Hi Mike, Im a new kid on the block and was scrolling through the site and posts and came across yours and noticed its been a while since there has been an outcome to this post.
Im no expert but it seems to me you are pulling too much water through the nexus with a 4 inch pipe coming from the filter to your pump, reducing the pipe to 2 inch from the filter to the pump should slow the water down a bit so the level wont drop, in a sense the filter is an obstacle in the way of water flowing freely through from bottom drain to pump therefore the flow of water is slowed in the filter but your pump is pulling it out faster than it can fill and the water has found an equilibrium point.
I am in the middle of pond construction at the moment and have been thinking of a nexus and everything ive read on the subject 1 answer comes up all the time, and thats "getting the flow right" then the nexus is a blinding bit of kit.
Must say that I’m still of the view that the problem doesn’t lie with the Nexus but the inlet pipework.
Basic problem is that the level in the Easy is too low when the pump is running, ie 6” down, differential you have between the Easy and the Bio chamber (another 2” is pretty normal).
If there were a blockage between the Easy and the Bio chamber there would be a greater differential than 2” (particularly with the Easy level being so low) so it doesn’t look like a problem there.
Pump may be marginally pulling through slightly more than the recommended max for the 300 but you should not be getting a head loss of 6” through 4” pipe with this kind of flow.
Ok a smaller pump will avoid the symptoms but would think it worth trying to establish the underlying problem. May be an idea to speak to Harvey at EA, he may be able to give you some ideas of typical head loss in the Easy with varying flow rates.
Not posted recently due to this particular Nexus being switched off,reason being it just got worse.the Bio section just kept getting lower and lower until it reached the point that it was at the bottom of the grid where the water returns.
This suggests to me that the water is not transferring from the easy section to the Bio quick enough,have a day off tomorrow so going to drain the Nexus down completely and see if there is a blockage and then back flush as Jules recommended earlier.
Carl
I take your point about the 4" return to the pump,I did it for two reasons;
1. the pump came with a nice ready made connector straight to 4" and
2. Everyone told me the Optimax was a frugal pump if just moving water with no obstacles hence the 4" pipe.
This pump is probably pumping back to the pond with a head of a little less than 1 metre but through probably 3 metres of 2" pipe with several twists and turns
Have to say if it is truly 85 watts its a cracking little pump.
The other Nexus is running on a old Aquamax 10,000 and there is hardly any noticeable drop in levels.
Ive been in this position; when the level in the Easy drops to a certain level the flow through it into the Bio drops off. Still think that a head loss of 6" in the Easy is your problem and that there is a restriction somewhere in the pipework to the Nexus.
My problem was the BD set too low, (but it could have been a blockage) I had son in the pond adjusting this and could see the immediate response to the head loss in the Nexus as he raised the cover.
My BD is def set to a generous 2" clearance,I am expecting a long day tomorrow draining it down giving it a good going over ! I intend also to dismantle the pipe work back to the rubber boot and purge the drain to see what happens.
I do know that up until I closed down this Nexus when I closed the valve and emptied the easy ,upon opening the valve the water briefly came out over the top of the Nexus spilling on the floor until it levelled off.
Yesterday,drained it down removed all K1,removed it from its position had a good look around it ,turned it up side down! nothing appears to be abnormal. Purged bottom drain ,satisfied that there are no restrictions there.
Put it back into position connected up and switched on,initially it ran as I would expect the input to the easy was about 2" down on the pond level and the Bio about 2" on the easy.This continued for the rest of the day,this morning the easy level is roughly the same but the BIO is some 9" lower than the easy,which suggests the flow from the easy to the bio is no9t quick enough or the pump is way to powerful ?
It has 6 x 2" 90 Degree bends and about 3 metres of 2"pipe from the pump to the pond ,the pump is an Optimax 15000 is fed from the Nexus right up to the pump by 4" pipe and has no other restrictions
Can you do a little video for me of the water that gets backflushed from th eouter chamber to the inner chamber?
If you turn the pump off and allow the water to equalize. Put your 3 inch pipe in the centre as usual and either clean the Eazy or just drop the centre chamber. Once the water is gone take out th ecentre pipe and film for me the amountg of water coming from the outer chamber back into th eEazy. Either send it to me as an email or send it to my by phone. I just want to gauge how much "backwash" you are getting.
Well looks like you are making progress, Jules is, as usual, along the right lines; sure I have heard of the odd unit that has a moulding problem in the pinch area.
6 x 90 bends; are these swept? Any chance of being able to connect some 2" flexi pipe to the pump so you can measure the actual flow?
2,000 ltr per hour may just be a tad too much pull from the filter but as with all things a level of tolerance would of been built into and with the restrictions of tthe bends added I wouldn't expect a loss in head of 9 inches. This is another reason why I want to see how "strong" the flow is when the centre pipe is removed from the Eazy to backwash the kiss points.
