Pump issues... please help

pmplumber · 23-11-2011, 05:15 PM

i have just built my 2500 gallon pond, installed my nexus 300 with answer. when i run my pump it is pulling the water out of the nexus before my 4 inch bd has chance to keep up. this is making pump noisy and dragging air. can someone tell me what size pump i need to acheive a turnover rate of no more than once every 2 hours. and if anyone is selling a pump please let me know.. many thanks guys

markf1fan · 23-11-2011, 05:45 PM

hiya

what pump are you using at the moment, i dont know much about the nexus but i would be looking at a 10,000L pump. maybe some others using the nexus will help you more.

mark

Koipondconstruction · 23-11-2011, 06:22 PM

What pump are you trying to run at the moment ??

If its just for filter use and then back to pond id opt for something like superfish 8000, same as aquamax but better and a lot cheaper with a 5yr guarantee. This will give you a more realistic flow rate around 1500 gph.

freddy · 23-11-2011, 06:25 PM

Hi.

I'm kinda surprised that your B/D can't keep up. It could be that the pump is too powerfull, but it might be that your Nexus is at the wrong level relative to the surface of the pond? Also, have you checked to make sure there are no blockages or obstuctions? I know virtually nothing about the Nexus, so hopefully someone more knowledgeable will be able to advise further.

Cheers...Freddy.

keithatrax · 23-11-2011, 07:31 PM

Maximum for a nexus 300 is 13000litres/hr. what are u using at the mo? Like Freddy said u might have an obstruction in your bottom drain or u may have too many bends or too long a pipe run. Hope this helps

Finflapper · 23-11-2011, 07:41 PM

Hi pmplumber , Sounds as if you have a serious restriction somewhere mate !
The Nexus will handle more than your pond per hour for filtering.
Also a 4 inch bd will deliver water many times over the rate which a pump is needed.
So, most pumps for ponds do not pull or suck water they push water once it is delivered to them, thus a submersible speaks for its self and a dry running pump (fitted outside the pond) must be below the water level of the pond or in gravity fed systems on the floor so water will self run to the pump.
Your pump is not getting pond water delivered to it ! The only restricting part of the nexus is the central static chamber of k1. If this is clean there must be a valve problem or a restriction in the bd.
A 2 inch supply to the pump is reccomended with the same following on to the returns. As you want a 2hr circulation an 8000 pump would be about right.
Check out the Nexus to make sure nothing is blocking the bottom of the centre pipe that takes water down to the outer chamber and check the outlet grill and the bottom of the sump that connects to the pump.
With the pump removed water should be gushing out the supply pipe !
Good Luck !

pmplumber · 23-11-2011, 08:23 PM

thanks a lot for the advice guys. my bottom drain is as clear as a bell. when i disconnect it from the nexus and open the 4" slide it absolutely gushes out, the nexus is spot on with the water level as the manufacturers recommendations. all i can think is the pump is way too powerful. it sucks the water out of the outer chamber faster than the inner staic chamber can put it through to the outer one, if that makes sence??? iv removed answer and tried the sponge but that makes no difference either.the water in the inner chamber is turning very fast too. all that is on the pump is itt marlow 1/2 hp. i cant find any info on it either. so i need a 8000 ltr pr hr pump? if so do i need a sequence pump and what exactly is a sequence pump? sorry to be a pain.

Finflapper · 23-11-2011, 09:49 PM

Hi mate, well your marlow probably shifts around 16000 litres per hour hour so it could well be the over the top and it quite possibly has suction too as alot of these pumps are used for transference at a fair lick. Big cost in power to run as well.

Sequence pumps are a brand of pump sold by Evolution Aqua to run with their Nexus. They are quiet and give large flow rates at low running costs. In a few years they can pay for themselves in running cost savings.

There are of course other pumps on the market up for the job.

If you have a valve after the pump, going to a uvc for instance, the valve can be used to regulate the flow back to the pond if needed.

pmplumber · 23-11-2011, 10:27 PM

yes well iv tried to throttle it down but the pump starts screaming. so ill get an 8000 ltr sequence. can i adjust the flow on a sequence if i need to?

go54nke · 24-11-2011, 12:07 PM

Something doesn't add up here.....

My mate runs a 300 off an aquamax 16,000 with no pipework restrictions, I run a 200 off an optimax 20,000, it does have a take off to feed the showers too but I can shut the shower side down and pull 20,000 through the 200 with no problems, and thats on 3" pipework!!!

Sequence 8,000 is too small for a 300, I would run at least a 12,000.

Just a thought, have you tried backflushing the 300 as the kiss ports may be blocked with K1?