Prevent Pump Hose From Clogging

[combatwombat]

I think non-metallic flexible conduit would work just fine if that's what you can get locally. It's basically the same stuff as flex pvc, but with a UV inhibitor. Per electrical code in the US, you're not allowed to use pvc glue fittings for that, but it's only because it's not listed as compatible—likely because the manufacturers make more expensive compression fittings to sell, so why bother listing a cheaper, generic fitting?

If you read some electrician forums, you'll find that it's solvent-welded w. pvc fittings all the time and seems to work very well. I've also read pond forums where it's been used without issue. I'd give it a try if it's all you can get.

 

[Ratsima]

I think non-metallic flexible conduit would work just fine if that's what you can get locally. It's basically the same stuff as flex pvc, but with a UV inhibitor. Per electrical code in the US, you're not allowed to use pvc glue fittings for that, but it's only because it's not listed as compatible—likely because the manufacturers make more expensive compression fittings to sell, so why bother listing a cheaper, generic fitting?

If you read some electrician forums, you'll find that it's solvent-welded w. pvc fittings all the time and seems to work very well. I've also read pond forums where it's been used without issue. I'd give it a try if it's all you can get.

Thanks for that information. I will keep searching. I've been dealing with this for 15 years now, so a few more weeks of looking around won't kill me.

 

[Ratsima]

I have one further thought on this. Most of the advice I've received indicates that a large hose diameter will help with this issue.

But I wonder if it might be that a larger hose actually exacerbates the problem. Given a constant volume of water output by the pump, the velocity of the water will decrease as the hose diameter increases and, conversely, the velocity of the water will increase as the hose diameter decreases.

Would the decreased velocity in a larger hose actually permit more formation of biofilm on the hose walls and an increased velocity in a smaller hose tend to discourage the adherence of biofilm on the hose walls? Or does the water velocity not matter when it comes to biofilm formation?

Any Fluid Dynamists out there?

 

[poconojoe]

I have one further thought on this. Most of the advice I've received indicates that a large hose diameter will help with this issue.

But I wonder if it might be that a larger hose actually exacerbates the problem. Given a constant volume of water output by the pump, the velocity of the water will decrease as the hose diameter increases and, conversely, the velocity of the water will increase as the hose diameter decreases.

Would the decreased velocity in a larger hose actually permit more formation of biofilm on the hose walls and an increased velocity in a smaller hose tend to discourage the adherence of biofilm on the hose walls? Or does the water velocity not matter when it comes to biofilm formation?

Any Fluid Dynamists out there?

I'm just totally puzzled as to what exactly is causing it to clog.
How come no one here has ever had that problem?

Could it be the garden hose? That's the odd factor. I don't think many people use garden hose for pond hose, but I could be wrong.
Is it really the gunk slowing the water or is the hose collapsing because it's too soft?

You would think the force of the pump would keep the hose clear. Strange...

 

[Ratsima]

I'm just totally puzzled as to what exactly is causing it to clog.
How come no one here has ever had that problem?

Could it be the garden hose? That's the odd factor. I don't think many people use garden hose for pond hose, but I could be wrong.
Is it really the gunk slowing the water or is the hose collapsing because it's too soft?

You would think the force of the pump would keep the hose clear. Strange...

Indeed. The garden hose is very robust and probably not collapsing. However, it may be kinking where it goes through a 2" PVC "passage" which has a 90º bend. The gunk might accumulate where the hose kinks.

To test this I have removed the hose from the PVC and draped it over the side of the pond. If it is a kink at that point, the blockage should stop as there can be no kink now.

The total volume of the gunk I recovered during the last hose cleaning is less than one tablespoon and weighs only 20 grams. How could that block a 5/8" hose with a 5000 l/h pump behind it?

 

[Lisak1]

We call that "pond snot". That's the stuff that will clog a filter pad up, too. I don't think it comes from the pond itself - I think it's a form of algae or biofilm that grows from whatever it being filtered out of the pond. Can you put a pre-filter on your pump? (Sorry if that's already been recommended and tried - I didn't go all the way back to read!)

 

[Ratsima]

We call that "pond snot". That's the stuff that will clog a filter pad up, too. I don't think it comes from the pond itself - I think it's a form of algae or biofilm that grows from whatever it being filtered out of the pond. Can you put a pre-filter on your pump? (Sorry if that's already been recommended and tried - I didn't go all the way back to read!)

What exactly is it that the filter would be filtering out?

I'm not convinced that maintaining a pre-filter would be any less inconvenient than having to ream the pond snot out of the hose every few days.

 

[Ratsima]

Indeed. The garden hose is very robust and probably not collapsing. However, it may be kinking where it goes through a 2" PVC "passage" which has a 90º bend. The gunk might accumulate where the hose kinks.

To test this I have removed the hose from the PVC and draped it over the side of the pond. If it is a kink at that point, the blockage should stop as there can be no kink now.

The total volume of the gunk I recovered during the last hose cleaning is less than one tablespoon and weighs only 20 grams. How could that block a 5/8" hose with a 5000 l/h pump behind it?

Unfortunately, that test failed. So, at least I know that it's not a kink or bend in the hose that causes the clogging.

Bypassing the 90º bend.

I suppose it could be the hose. Is there any particular type I should use? The current 5/8" opaque garden hose replaced a ½" clear plastic hose that I used for years.

 

[GBBUDD]

Pistia

I don't think many people use garden hose for pond hose,

garden hose is not for potable water too use the hose to top off or even fill a pond is fine but cheap garden hose can have a nasty taste to them and i doubt the fish would benefit from it either.

the other issue in a narrow diameter hose. is sure you could start to choke the line down if you have an algae problem and your pump only pushes low volume. i had algae explode when i introduced co2 to my planted fish tank years ago the spray bars and returns only having up to 1/4 holes clogged and had to be picked clean

 

[Ratsima]

The only fish I have in my pond are guppies. At most there are about 20; all of which are less than an inch (2.5cm) long. I've never had an algae problem. The pond is always crystal clear unless I've stirred up some sediment culling the water Lilly.

 

[poconojoe]

Just taking a wild long shot guess...

Do you think it could be the material the garden hose is made of? Maybe its soft and porous. Easier for the "pond snot" to grab hold of?
Maybe pvc would be smoother, slicker and hard to grab hold of?

Or, is the answer simply that you need a larger I.D. hose (or pipe)?

 

[poconojoe]

The only fish I have in my pond are guppies. At most there are about 20; all of which are less than an inch (2.5cm) long. I've never had an algae problem. The pond is always crystal clear unless I've stirred up some sediment culling the water Lilly.

Guppies!
Cool! I love those!

 

[Ratsima]

Just taking a wild long shot guess...

Do you think it could be the material the garden hose is made of? Maybe its soft and porous. Easier for the "pond snot" to grab hold of?
Maybe pvc would be smoother, slicker and hard to grab hold of?

Or, is the answer simply that you need a larger I.D. hose (or pipe)?

I'm attaching a couple of photos of what the hose looks like on the inside. The green color is just a thin coating. Inside the hose is black and smooth, but not absolutely smooth.

I will go to the hardware store today to see what's available. The only difficulty with a larger ID is that it won't fit through the bend that I've built in to the pond. Changing that will involve breaking a lot of cement and rock and re-doing that section of the pond edge. I'm hesitant to do that unless I'm positive it will solve the problem.

This is where the hose enters a 2" PVC pipe to exit the pond. I broke away some of the pipe to lessen the bend in the hose, but that didn't do much. As you can see, the 2" PVC is embedded in cement and granite rocks.

 

[Ratsima]

I spent much of today cycling to a couple of local hardware stores and searching online for a suitable hose for my pond. I couldn't find anything available locally. The following is available from Amazon US and will ship to Thailand (for more than the hose costs). Would this be a reasonable replacement for my pond's garden hose?

Tetra 1" Pond Tubing
.

 

[combatwombat]

If you’re going to pay for shipping, don’t get that. Get flex pvc. Are you certain this is going to fix your problem, though?