Drip system problem

[GAS]

I have bin running a drip system for a year now... lately the flow starts good and then slows down to a stop. I thought it was the pump going bad (350gph little giant). Replaced with 350gph little giant direct drive and having same problem. The weird part is if you turn the pump off and turn it back on the flow starts with a good stream and slows to none.
The system has a 5/8 main line with 1/8 feeder lines. They do not look cloged and you can blow through them fairly easy. Any thoughts??

 

[quazzy10]

If you've changed the pump it can only be blocked lines, i know you can blow down them but if they have a build up inside it can close up with water pressure and will restrict the flow, for the price of them i would change all the lines and get another year of trouble free growing and at least you have the old pump as a back up too.

 

[gangjababy]

run some clearex thru the lines or use a similar product...

 

[bonze309]

I would replace the lines with new Its really cheap its better then having all the trouble

 

[Al B. Fuct]

The weird part is if you turn the pump off and turn it back on the flow starts with a good stream and slows to none.

Wow, interesting problem. Any chance the pump is sucking air? If an air bubble is trapped in the impeller chamber, it can cavitate, just churning air & water in the chamber, causing it to stop pumping. Turning it off then on again may give the bubble time to clear. Just guessing wildly, but that happens to my pumps sometimes. When my flood systems drain back, vortex action may draw some air down into the pump impeller chamber. If the outlet is pointed upward, the problem doesn't seem to happen.

 

[GAS]

I would agree changing out the lines would be an easy cheap fix. The part that puzzels me is it starts strong and peters out. If they are pluged would'nt they start slow?

 

[Al B. Fuct]

Yeah, that's the part that has me going. It's like there's something in the lines that obstructs flow only when there's water flow. I thought about some algae buildup that might be moving into the path when there's water flow, but you say they don't look clogged and air goes thru OK.

Could you rig up a temporary gravity feed to replace the pump to see if the problem is in either the pump or in the lines?

 

[GAS]

Thanks for the guess Al b. The pump is fully submerged. I have put my finger over the inlet of the pump after the lines quit flowing... there is some suction but not much after doing that it will start flowing again but slow to stop. Is it possible to something in the lines that build up under presser?

 

[Al B. Fuct]

If you can lay your hands on some 50% grade H2O2, you might run a strong (10ml/L) solution through them to kill and remove any algae, fungus etc.

I wonder perhaps if there's chips of dried nute salts moving around in the tubes. Can you backflush them?

 

[GAS]

O... another weird thing there are 10 lines and they all slow equally. It would make more sense if it were only some of the lines.

I have no more room to put up a gavity feed. I think I might replace the whole line.There must be something in it some where...

 

[GAS]

Back flush... good idea why did'nt I think of that.Thats why your the man! I just need to limp along another week and I will be cutting down. I will take the lines out and flush them befor the next crop goes in.

 

[Al B. Fuct]

That tells me that if there's an obstruction, it's in or before the manifold.

Replacement sounds like a good option, if backflushing doesn't sort it.