Flexible PVC Pipe (solvent weld)

[Ratsima]

That effect is negligible, hence I think that the likely cause of the problem is hose kinking, as suggested by Scout earlier.

I did an experiment where I removed the hose from the PVC with the bends and just draped it across the pond edge. So, no bends in the hose and no kinks.

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Sadly, after just over 24 hours the flow through the fountain is just a dribble. So, it is not kinking that causes the problem.

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This is what it looks like after I ream out the hose:

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I'm at a loss now.

[Ratsima]

There's a long thread on this problem on a pond forum. I started it in 2015 and recently revived it:

Prevent Pump Hose From Clogging

One interesting thing is that none of these pond enthusiasts has come across a similar problem where the hose gets clogged by algae, biofilm or whatever, but no biofilm or algae appears anywhere else in the pond.

The rest of my pond is always crystal clear and, for the most part, algae free. The only algae I ever see is the string algae which only forms in the pond stream and usually only during the "winter" months when the sun can shine directly on the stream. Right now there's no visible string algae at all.
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Here you can see the stream. It is about 30-40 cm deep and filled with gravel and sand and serves as a sort of "natural" filter. I believe that this filter is why the pond itself is always crystal clear and free of visible algae.

In any event, I'm stumped over the hose issue.

[Ratsima]

Once the algae takes hold in the hose, it forms sheets that dislodge when the flow starts; this sheet is the thing that clogs the fountain outlet. I have had this problem every time I used the garden hose to connect to my high pressure washer. Once the algae is established, it won't go away.
You have a couple of choices.
1. Change the hose every couple of months. Make sure you clean the inlet nozzle that you connect the hose to if you have one to make sure it is algae free from the start.
2. Disconnect the fountain from the main line and just use a solar-powered one. It'll run only during the day, but will you really notice it at night?
3. If you worry about the fish, get a seperate aquarium aerator pump. I don't think the water flow alone would introduce enough oxygen, but that's my opinion.
Don't bother with varying diameters or hoses, the problem is the algae.
I got around my problem by using a seperate dedicated hose connected to the pressure washer. It is always disconnected and drained after each use.

I've got no problem with frequently changing the hose.

• What sort of hose should I use and what ID?
• The pump feeds the fountain. There's only one line. I suppose I could put a timer on it so the pump is off and the hose dry at night.
• The pond only has a couple of dozen guppies, less than an inch long. They are only there for mosquito control. I gave up on larger fish because predatory birds kept eating them all.

[Nereus]

Having nothing better to do I have read through ALL of the posts on the forum link that you posted.
The pump supplier must really love you as I lost count of how many different pumps that you have tried!

I have also read a lot of other articles and am now of the opinion that it has absolutely stuff all to do with any pump, filter, hose, plants, kinks or phi.

The problem is the conditions are conducive to producing BIOFILM, as you have written, NOT Algae or organic rubbish. The fact that it adheres to the inside of the hose is simply because that is the only place where it is being transported to.

What is producing it is the unknown, and in fact, one of the remarks somewhere says that there is nothing on the market known to stop it, and if there was, that you should not use it!

Wiki has the following to say about it, and althoughh some of it is medical, the principle is the same.

https://en.wikipedia.org/wiki/Biofilm

[cookie102]

I know that this may seem a bit easy but the type of hose you are showing can laminate internally and cause a loss of flow and give somewhere to cause blockage. If this is the case each time you clean it internally it may be only correcting it for a short time.
Sorry if its a stupid suggestion but worth a look.

[Ratsima]

Having nothing better to do I have read through ALL of the posts on the forum link that you posted.
The pump supplier must really love you as I lost count of how many different pumps that you have tried!
<snip>
What is producing it is the unknown, and in fact, one of the remarks somewhere says that there is nothing on the market known to stop it, and if there was, that you should not use it!

So, after reading the voluminous information on the Garden Pond forum and elsewhere it is your opinion that there's absolutely nothing I can do about this except continue to periodically ream to hose, as needed?

And, yes, I have horrible luck with certain items. I go through two or three pond pumps per year. I have dozens of bicycle flats per year. (A friend here in Korat who rides more than I do and has also been here for more than 15 years has never had a flat on his mountain bike.) I also go through hard drives like they were candy and I don't want to even get started on how many batteries of all sorts we go through.

Bad Karma.

[Ratsima]

I know that this may seem a bit easy but the type of hose you are showing can laminate internally and cause a loss of flow and give somewhere to cause blockage. If this is the case each time you clean it internally it may be only correcting it for a short time.
Sorry if its a stupid suggestion but worth a look.

Can you elaborate on this a bit? By "laminate internally" do you mean that one inside wall of the hose sticks to the opposite inside wall?

I don't think that could happen with this hose. The walls are actually quite robust. I cannot squish it flat with just two fingers.

[Nereus]

I also go through hard drives like they were candy and I don't want to even get started on how many batteries of all sorts we go through.

And Puyings, are they a problem

I think that you mentioned it, but anyhow, if you can manage to coach 2 x 15 mm hoses down the conduit, rig up a change over valve somewhere near where the hoses enter the conduit, or near the pump discharge, and change them over when one becomes blocked. The one not in use may dry out enough to flush the crap through next time you change over the supply.

[hin]

I wont bother to highlight a lot of info already submitted above but based on that info plus my own experiences here are some of my opinions:

I might be wrong but the amount of sludge you are getting seems to go beyond microfilm.

For a bit of back story, when we bought our house we had to completely re-grout the pool because a lady hired to take care of it had the theory that maximum water treatment = minimum work for her. But the excess chlorine and acid she dumped into the pool ate up all the grout. As a result of that I became a light handed minimalist with water treatment but did stay on top w frequent and complete water testing - chlorine, pH, total alkalinity, TDS, cyanuric acid, the whole bit. But then changed to a salt water system and it keeps the chlorine so well controlled and stable that I rarely bother to test anymore, just watch for visual signs that attention is needed.

The water is always crystal clear. Algae will not show in the water unless beyond extremely severe. Green algae normally settles on the bottom and can be vacuumed into the pool’s sand filer then back-flushed out into our garden to make the flowers grow. Black algae is a different matter - it sticks to things.

True: algae prefers some surfaces over others and some black algae thrives best in absence of light. Our pool has 4 styles of tile plus the grout, and algae does not grow on the smooth shinny tiles but on the steps there are some white ones with a sandpaper-like finish and when those start to go black its time to add acid to the water. Also when small black slightly gelatinous spots begin to appear on a few places on the grout it is time to add acid. It does not take much, about ½ liter of hydrochloric acid does the job in our small pool - 23 cubic meters (23000 Liters) but of course the water is also chlorinated. Unchlorinated water would cause a difference, test the pH and try for 7.0-7.8.

True: There is algae resistant hose available in the USA. Because so many people live in house trailers and they hook up to the mains with a hose. It usually has a teflon lining. But we have replaced all our garden hoses with that blue vinyl garden hose available here and it seems to stay clean inside plus is very flexible so does not kink when coiling or uncoiling or bending it. Most good hardware stores have big coils of it and will cut off whatever length you need or want.

True: If algae is in your system, control is easier than eradication because you can only truly get rid of it with biocide which would also kill yr fish and plants and would need to continue adding biocide every time you add water bcuz that is where it is coming from. Altho we put clean water in our dog’s bowls every day, black algae will start to show if we do not also wash them every few days. Also of note, we use 5” and 6” PVC water pipe caps for our dog bowls. The 5” one is simply cast smoothly and algae never appears but the two 6” ones are cast with almost machined looking sharp inside corner at the bottom and that is where the black algae begins to form. (These are very practical heavy dog bowls and can be bought anyplace that sells large diameter water pipe..)

True: A filter will block algae, But it will not block the spores. The spores will carry on right thru the filter and grow into new algae after the filter.

My suggestions would be go to a swimming pool supply store to buy some simple pH test strips to dip into the water to see where the pH is. Definitely get rid of that hose and replace it with a blue vinyl one and if the black algae continues or especially if it begins to appear in other places in the pond I would try adding some acid to the water. When doing this type of construction always use long sweep electrical conduit elbows if hose or wire will be passed thru them, not the tight bend 90˚ er even 45˚ water pipe elbows.

[Nereus]

I know that this may seem a bit easy but the type of hose you are showing can laminate internally and cause a loss of flow and give somewhere to cause blockage. If this is the case each time you clean it internally it may be only correcting it for a short time.
Sorry if its a stupid suggestion but worth a look.

Can you elaborate on this a bit? By "laminate internally" do you mean that one inside wall of the hose sticks to the opposite inside wall?

I don't think that could happen with this hose. The walls are actually quite robust. I cannot squish it flat with just two fingers.

What is meant is "delamination", where the surface of something breaks away from a base material, usually where two different materials are in contact.

[Ratsima]

I wont bother to highlight a lot of info already submitted above but based on that info plus my own experiences here are some of my opinions:

I might be wrong but the amount of sludge you are getting seems to go beyond microfilm.

For a bit of back story, when we bought our house we had to completely re-grout the pool because a lady hired to take care of it had the theory that maximum water treatment = minimum work for her. But the excess chlorine and acid she dumped into the pool ate up all the grout. As a result of that I became a light handed minimalist with water treatment but did stay on top w frequent and complete water testing - chlorine, pH, total alkalinity, TDS, cyanuric acid, the whole bit. But then changed to a salt water system and it keeps the chlorine so well controlled and stable that I rarely bother to test anymore, just watch for visual signs that attention is needed.

The water is always crystal clear. Algae will not show in the water unless beyond extremely severe. Green algae normally settles on the bottom and can be vacuumed into the pool’s sand filer then back-flushed out into our garden to make the flowers grow. Black algae is a different matter - it sticks to things.

True: algae prefers some surfaces over others and some black algae thrives best in absence of light. Our pool has 4 styles of tile plus the grout, and algae does not grow on the smooth shinny tiles but on the steps there are some white ones with a sandpaper-like finish and when those start to go black its time to add acid to the water. Also when small black slightly gelatinous spots begin to appear on a few places on the grout it is time to add acid. It does not take much, about ½ liter of hydrochloric acid does the job in our small pool - 23 cubic meters (23000 Liters) but of course the water is also chlorinated. Unchlorinated water would cause a difference, test the pH and try for 7.0-7.8.

True: There is algae resistant hose available in the USA. Because so many people live in house trailers and they hook up to the mains with a hose. It usually has a teflon lining. But we have replaced all our garden hoses with that blue vinyl garden hose available here and it seems to stay clean inside plus is very flexible so does not kink when coiling or uncoiling or bending it. Most good hardware stores have big coils of it and will cut off whatever length you need or want.

True: If algae is in your system, control is easier than eradication because you can only truly get rid of it with biocide which would also kill yr fish and plants and would need to continue adding biocide every time you add water bcuz that is where it is coming from. Altho we put clean water in our dog’s bowls every day, black algae will start to show if we do not also wash them every few days. Also of note, we use 5” and 6” PVC water pipe caps for our dog bowls. The 5” one is simply cast smoothly and algae never appears but the two 6” ones are cast with almost machined looking sharp inside corner at the bottom and that is where the black algae begins to form. (These are very practical heavy dog bowls and can be bought anyplace that sells large diameter water pipe..)

True: A filter will block algae, But it will not block the spores. The spores will carry on right thru the filter and grow into new algae after the filter.

My suggestions would be go to a swimming pool supply store to buy some simple pH test strips to dip into the water to see where the pH is. Definitely get rid of that hose and replace it with a blue vinyl one and if the black algae continues or especially if it begins to appear in other places in the pond I would try adding some acid to the water. When doing this type of construction always use long sweep electrical conduit elbows if hose or wire will be passed thru them, not the tight bend 90˚ er even 45˚ water pipe elbows.

So much advice; much of it contradictory.

20 grams of gunk over a 48 hour period doesn't seem like a lot, but what do I know?

A few years back I bought test kits at an aquarium supply place (I still have them). As I recall, the pond water was always at 7.0 or slightly above. When it stops raining, I'll test again. (Of course, all the recent rain will have an effect on the pH.

To be honest, I'm a bit weary over the whole topic by now. Maybe it's simpler to just continue reaming out the hose now and then.

[laser]

That effect is negligible, hence I think that the likely cause of the problem is hose kinking, as suggested by Scout earlier.

I was looking into the hydraulic aspects (unusual/interesting case!), besides that you obviously thought about changing the hose as the simplest/cheapest possible solution. It's difficult to see how would a few mm diameter reduction ruin the flow rate. I used vague assumptions with the only data being the hose size, so the figures certainly can be off & wrong.

Just knowing two flow (=pump discharge) rates, for 'clean' and 'dirty' conditions would help understanding the situation. Can you do a bit of engineering, please? The measurement is simple & easy: mark say 10, 15, or 20 L water volume on some bucket/container, then measure the time (seconds) to fill that volume by the 'fountain' outlet jet.
With those data much would be revealed already, though also would be useful to know the:
- length of the hose
- static lift (elevation difference between the water surface level in the pond and the end of the hose (discharge point)
- immersion depth of the pump
I guess the Chinese don't provide the Q-H (performance) curves for their pumps but for such type of pumps those all look very similar/simple.
Such data (or estimates) are important because changing the hose diameter also changes the pump working point (pump fdischarge and head).

The ultimate cause of the problem is evidently biofilm growth but discussing the reasons and management options IMO can wait for the hydraulics results. It suffices to say that there's no algae problem -> using any algacide would be a mistreatment.

[Ratsima]

I will do that. I'll get a "dirty" flow rate just before I clean the hose next and a "clean" flow rate just after. I'll supply the other measurements thereafter.

The static lift will have to be an estimate unless you can suggest a way to get a more precise measurement.

[edit] Scratch that, I got it. As soon as the rain stops.

[cookie102]

What I was referring to is the exterior of the pipe is green plastic and the inside black so there must be some kid of bonding between the two layers. I have seen it when the inside layer comes away from the outside ( even over a very small area) which can cause a restriction in the pipe inside diameter giving an area that sludge can quickly form.
As I said before it may be a stupid suggestion.

[Ratsima]

As I said before it may be a stupid suggestion.

Not at all stupid. It's a valid observation that I failed to make myself.

I'm not sure how I would check for it, but I'm now fairly determined to buy a better quality hose; not a garden hose but one actually designed to purpose.

I appreciate your taking the time to make the observation and the time to make sure I understood what you had observed.

Thanks for being persistent.