pond diy UW housing leakage issue

I have  a pond and once had an underwater PoE camera hooked up.  Well, it developed two problems in the year and a half and then the camera died.  I don't want to keep replacing the unit as it's not cheap, so I've been working on a 'reusable' underwater housing where I can put in inexpensive PoE cameras as they break, which seems likely.  In working out the design, I'm using pvc, glass for a front lens, and a customized endcap with rubber o ring + latches.  Now, I'm using flex pvc (3/4") as a shield tube at that end port as I need to get the ethernet cord from the cam and up to the surface where it connects with a coupler and then to the feed to the PoE injector.

The camera will be in a freshwater pond where water temps will range from 35F to 85F, approx 20" down.  The camera is a Reolink 5mp security PoE cam which gets power from a PoE injector, then on to the computer.  Since ruining the original ethernet connector (looks like water got in), I've now got a waterk-proof taped solid lead from cam out of the housing and to the coupling above water.

I've had multiple issues with leaking and couldn't understand until maybe, just yesterday, had a thought; I'd put silicone on every seam, even the ones where I glued pvc to pvc and where the flex pvc attaches, then siliconed the end of the plex pvc to make it air tight.  (I'm aware silicone isn't a good 'stick' for pvc but have it so the outside water pressure should push against any silicone and force it tighter.  If  I don't mess with it, it stays attached and functionable.   The one time I DID mess with it, I got leakage).  I still got water, not a lot, but apparently enough to ruin an ethernet cord end.  Fixing this, I then mounted the cam back in the case and let it do it's thing without any silicone to cap off the flex pvc end, effectively allowing air to get in and out.  Yesterday, I was going to rework the silicone and when I opened the diy case, I had a teaspoon of water come out.  Now, this is OUT of the water.  Sooo, long story short, I think the cam is taking humidity out of the air and it's pooling up inside the case.  I expect this may account for my earlier water inside, thinking then it was from faulty joints/sealing.  I DO have a packet of silicone absorbent granules inside, just for the purpose of taking out any humidity.  I assumed once gone, the air would then NOT deposit out and ruin the cam/cam cord connection.

So question for anyone having dealt with moisture in this sense, how do I insure I won't get such a buildup of water?  Do I have to manually extract the air right after gluing/latching?  I've heard to put in CO2/Nitrogen but I don't have easy access to this and am just looking for some sort of 'trick' that will keep the camera inside dry for years (or yearly when it dies on me, again!).  I need to be able to get in and out of this housing, hence why I'm trying to overcome the problem.  I know I could seal it up permanently but I might as well just go the expensive UW cam route in that case.

I've also wondered if this ethernet cable (supposedly exterior/bury usage) is letting water in through it's jacket and if that is something I need address.

Any ideas?  I know it's not a typical subject--I've checked and googled ad nauseum--but any insights to either my build or my current issue would be much appreciated!  

Thank you in advance, esp for anyone who read all the way through!

brokensword

First of all a teaspoon of water seems like a lot to have condensed from the air - I assume the air volume in the camera is trapped inside?

Doing some calculations - air that is 100% humidity at 80F and assuming a volume of 1 ft3,  that volume of air contains 0.75ml of water and not all of that will condense, while a teaspoon is 5ml of water.  I would guess the volume of your housing is significantly less than 1 ft3 ( a cube 1ft on each side).  So if was sealed and you found a teaspoon of water in there it leaked in.  Air does not contain that much water.

As for the camera just sitting there in the air and water coming in and condensing - you need a driving force.  If the camera case is colder than the air outside it will come closer to being saturated in the case and some may condense if it's cold enough.  But if it's just sitting there on a bench it will be at air temperature  so temperature inside and out will be the same.  If the camera is on and as a consequence generating heat then that will not cause condensation.  Water condenses on surfaces that are colder than the outside air.

So I think you need to look elsewhere for the cause.  PVC plumbing fitting are by definition water tight if you use PVC cement on them following the directions. Your custom o-ring, the camera glass window  and the PVC flex whatever that is would be where I  would look first.  I would also read up on o-ring design, there's a lot of stuff on the internet for that.   O-rings are very effective seals - but they need to be loaded to work - there are a number of things that cause them to leak including grit and hairs across the seal face and the sealing surfaces need to be smooth.  Sealing against an Ethernet cable could also be an issue.

5 hours ago, ChrisRoss said:

First of all a teaspoon of water seems like a lot to have condensed from the air - I assume the air volume in the camera is trapped inside?

Doing some calculations - air that is 100% humidity at 80F and assuming a volume of 1 ft3,  that volume of air contains 0.75ml of water and not all of that will condense, while a teaspoon is 5ml of water.  I would guess the volume of your housing is significantly less than 1 ft3 ( a cube 1ft on each side).  So if was sealed and you found a teaspoon of water in there it leaked in.  Air does not contain that much water.

As for the camera just sitting there in the air and water coming in and condensing - you need a driving force.  If the camera case is colder than the air outside it will come closer to being saturated in the case and some may condense if it's cold enough.  But if it's just sitting there on a bench it will be at air temperature  so temperature inside and out will be the same.  If the camera is on and as a consequence generating heat then that will not cause condensation.  Water condenses on surfaces that are colder than the outside air.

So I think you need to look elsewhere for the cause.  PVC plumbing fitting are by definition water tight if you use PVC cement on them following the directions. Your custom o-ring, the camera glass window  and the PVC flex whatever that is would be where I  would look first.  I would also read up on o-ring design, there's a lot of stuff on the internet for that.   O-rings are very effective seals - but they need to be loaded to work - there are a number of things that cause them to leak including grit and hairs across the seal face and the sealing surfaces need to be smooth.  Sealing against an Ethernet cable could also be an issue.

Thank you, Chris, for helping.  I too was surprised at the amount of water and maybe it had been trapped somewhere from the previous test, but I thoroughly dried and inspected the camera before this latest test.  

My O ring junction is a 1/4" x 4ish inch ring that is put on the outside of a ground-down cleanout plug.  It then gets lowered into the tube (the female threaded end) and I have 4 latches that compress the ring so it's bound on top by 1/8ish pvc, on the bottom by similar, and on one side by the ground-down plug.  I silicone this whole cap, including the O ring.   I'm not sure it's being compressed (loaded, right?) enough, and maybe I have to re-mount the latches to guarantee this.  Seems pretty tight as I try to latch and unlatch the plug end.  Flex pvc is just that; flexible pvc tubing which can be fused using normal pvc solvent.  I'm using this as I need to route this ethernet shield up and out of the water and attach to the pond decor so as to hide it easier.  I started with all rigid but it got too unweildy.  Someone told me that plastics and silicone are permeable but I'm wondering exactly how, since aquariums are made using this and they don't leak.  I have the pressure of the pond water pushing toward most of the housing (I have to really weigh this down to keep it under water--a con with using plastics compared to my original expensive stainless steel bullet housing) so any silicone should be being pushed against as it would be in an aquarium, right?

I'm going to give it another test tomorrow, sans the camera, and see how much/if I get water again.  The next to previous test was fine, hence I tried with the camera and I got a little water.  Pulled it out, redid the silicone, put it out on dry land, let it video for a week or so, then opened it yesterday to find the water.  The previous time, I had sealed the flex pvc end, this last time--out of water--I didn't see the need, but am going to do it anyhow.  

I have dessicant  inside (3"x1" pouch) and it felt dry.  The camera does indeed heat up, so I figured any humidity would be airbourne and be absorbed by the dessicant, right?  I was surprised, like I said, when it poured out.  I'm hoping it was actually in the camera (didn't kill it, apparently, thank you very much!) and it's gone now.

btw, I DO have a more humid house as I have many plants and aquariums that contribute.  Not sure this makes the math any less real or accurate, but thought I'd mention it.  Do you have a better sealer that would allow me to gain access to the camera in the future than silicone?  And do you think water is getting into the jacket of the ethernet cord and hitting the cord end, thereby shorting/corroding the system?

Again, thank you very much; been working on this for the whole summer and can't seem to find the answer.  I bet I've tested this unit 7 times now with only once getting no water (the current configuration).

6 minutes ago, brokensword said:

Thank you, Chris, for helping.  I too thought was surprised and maybe there was water trapped somewhere from the previous test, but I thoroughly dried and inspected the camera before this latest test.  

My O ring junction is a 1/4" x 4ish inch ring that is put on the outside of a ground-down cleanout plug.  It then gets lowered into the tube (the female threaded end) and I have 4 latches that compress the ring so it's bound on top by 1/8ish pvc, on the bottom by similar, and on one side by the ground-down plug.  I'm not sure it's being compressed (loaded, right?) enough, and maybe I have to re-mount the latches to guarantee this.  Seems pretty tight as I try to latch and unlatch the plug end.  Flex pvc is just that; flexible pvc tubing.  I'm using this as I need to route this ethernet shield up and out of the water and attach to the pond decor so as to hide it easier.  I started with all rigid but it got too unweildy.  Someone told me that plastics and silicone are permeable but I'm wondering exactly how, since aquariums are made using this and they don't leak.  I have the pressure of the pond water pushing toward most of the housing (I have to really weight this down to keep it under water--a con with using plastics compared to my original expensive stainless steel bullet housing) so any silicone should be being pushed against as it would be in an aquarium, right?

 

I'm going to give it another test tomorrow, sans the camera, and see how much/if I get water again.  The next to previous test was fine, hence I tried with the camera and I got a little water.  Pulled it out, redid the silicone, put it out on dry land, let it video for a week or so, then opened it yesterday to find the water.  The previous time, I had sealed the flex pvc end, this last time--out of water--I didn't see the need, but am going to do it anyhow.  

 

I have dessicant  inside (3"x1" pouch) and it felt dry.  The camera does indeed heat up, so I figured any humidity would be airbourne and be absorbed by the dessicant, right?  I was surprised, like I said, when it poured out.  I'm hoping it was actually in the camera (didn't kill it, apparently, thank you very much!) and it's gone now.

 

btw, I DO have a more humid house as I have many plants and aquariums that contribute.  Not sure this makes the math any less real or accurate, but thought I'd mention it.  Do you have a better sealer that would allow meto gain access to the camera in the future than silicone?  And do you think water is getting into the jacket of the ethernet cord and hitting the cord end, thereby shorting/corroding the system?

 

Again, thank you very much; been working on this for the whole summer and can't seem to find the answer.  I bet I've tested this unit 7 times now with only once getting no water (the current configuration).

 

 

I'm sorry I don't really follow what you are doing with the clean out plug arrangement.  If you are using an actual o-ring then it needs to be contained.  By o-ring I mean a round cross section rubber ring.  The two main types of seal are face seals and cylinder seals, see this link for a diagram:  https://www.marcorubber.com/o-ring-groove-design-face-seal.htm and: https://www.marcorubber.com/o-ring-groove-design-face-seal.htm

All the sealing surfaces need to be smooth with no moulding marks etc as they provide a potential passage for water entry.

The calculation won't be impacted by a humid house, I assumed 100% humidity at 80F, that is the air is completely saturated and can't absorb any more water.

I assume by flexible PVC you mean clear PVC tubing.  I would be inclined to use a hose barb fitting like this one: 

https://www.ebay.co.uk/itm/131697726895?hash=item1ea9cbd5af:g:dt8AAOSwGotWm220

put a gasket underneath, use a hose clamp and some thread sealant as well, you would probably want one suited to 20mm tubing to have the hole through the fitting big enough.

I can't design it for you but I would encourage you to try to make it all from standard plumbing fittings the inspection hatches on those are designed to be watertight, rather than try to rely on silicone doing the sealing for you.  They often use flat gaskets which is OK as well. 

You can purchase things like underwater ethernet cables and bulkheads , but it tends to be pricey for example you can buy an ethernet bulkhead generally with an M16 fitting but the bulkhead runs something like $360 and the cable a similar price.   They are quite specialised.  The best approach is probably a tube you can pass the ethernet cable through but with a proper connector installed on your housing.

8 hours ago, ChrisRoss said:

I'm sorry I don't really follow what you are doing with the clean out plug arrangement.  If you are using an actual o-ring then it needs to be contained.  By o-ring I mean a round cross section rubber ring.  The two main types of seal are face seals and cylinder seals, see this link for a diagram:  https://www.marcorubber.com/o-ring-groove-design-face-seal.htm and: https://www.marcorubber.com/o-ring-groove-design-face-seal.htm

All the sealing surfaces need to be smooth with no moulding marks etc as they provide a potential passage for water entry.

The calculation won't be impacted by a humid house, I assumed 100% humidity at 80F, that is the air is completely saturated and can't absorb any more water.

I assume by flexible PVC you mean clear PVC tubing.  I would be inclined to use a hose barb fitting like this one: 

https://www.ebay.co.uk/itm/131697726895?hash=item1ea9cbd5af:g:dt8AAOSwGotWm220

put a gasket underneath, use a hose clamp and some thread sealant as well, you would probably want one suited to 20mm tubing to have the hole through the fitting big enough.

I can't design it for you but I would encourage you to try to make it all from standard plumbing fittings the inspection hatches on those are designed to be watertight, rather than try to rely on silicone doing the sealing for you.  They often use flat gaskets which is OK as well. 

You can purchase things like underwater ethernet cables and bulkheads , but it tends to be pricey for example you can buy an ethernet bulkhead generally with an M16 fitting but the bulkhead runs something like $360 and the cable a similar price.   They are quite specialised.  The best approach is probably a tube you can pass the ethernet cable through but with a proper connector installed on your housing.

 

 

Flex pvc is NOT clear, it's typically black but I've also bought it in white.  It allows connection to typical rigid sch 40 fittings.  The basic premise is; a 4" tube, glass lens on one end, cleanout plug on the other.  This cleanout is threaded.  My thought was I'd screw it in and out as needed, with pipe dope on the threads.  I still got leaks this way so I went with an round O ring,m 1/4" diam rubber with 4" diameter ring.  This fits snugly around the cleanout plug AFTER I ground down the threads on the male side.  The female side I left along as long as the male side slipped inside.  This O ring goes around the plug 'shaft' and top rim and fits against the bottom of the cleanout portion (female side) against it's rim.  So the O ring is open on one side.  This is where I cover with silicone, all the way around the tube end.  I installed 4 latches that pull the plug now into the bottom, compressing the rubber O ring.  The idea is I can then more easily take off the silicone when I need to unlatch the tube to replace the camera as opposed to permanently sealing the plug to the female end.  I then have sch 40 pieces pvc glued to the top of the plug where I've bored a 3/4" hole for the cable.  The flex pvc connects to the top parts and the cable is threaded inside.  The flex pvc is long enough to go from under the water to dry land where I have the main ethernet feed from the house.

I got rid of most of the threaded parts and went to glue BECAUSE I was getting leakage.  Now, only the latch + O ring.

Hope this clarifies.

I'll follow your links and see if I can modify/fix what I've got.  Thank you.

What I was proposing with the threaded piece was to use a gasket to get your water proofing with a nut on the inside so you are not trying to form threads in PVC- unless threads are perfectly formed taper threads it will be hard to get them watertight alone - so you use a gasket. 

The standard way of doing this on an underwater housing is a threaded plug with and o-ring set up to get the right amount of compression when you tighten it down.  You can take them in and out and they seal perfectly.

It sounds very much to me like the surfaces for the gasket are not flat enough.  Unless you do the machining on a lathe where you can control flatness and surface finish, you will struggle to get a good seal. 

You might see if you can get something like this one:  https://www.bunnings.com.au/holman-100mm-pvc-dwv-bolted-trap-screw_p4750162

It attached to tube with solvent cement.

ahh, I get it now.  I AM using factory produced parts but I'm sure they were never intended to have perfectly flat OUTTER edges like I'm using.  And with the O ring being circular diameter, I bet it's not compressing as you're indicating, either.  The piece you linked to; is there a gasket then UNDER the 'lid' that is held then by screws?  I can see that working just fine.  I'd have to bore the 3/4 hole and do more pvc gluing to complete the access end, but shouldn't be a problem.

Thank you!

[edit] I went looking but the part seems to only be available in Australia.  Is there something similar in the US?  I tried the cleanout plug with threads and didn't have any luck.

5 hours ago, brokensword said:

ahh, I get it now.  I AM using factory produced parts but I'm sure they were never intended to have perfectly flat OUTTER edges like I'm using.  And with the O ring being circular diameter, I bet it's not compressing as you're indicating, either.  The piece you linked to; is there a gasket then UNDER the 'lid' that is held then by screws?  I can see that working just fine.  I'd have to bore the 3/4 hole and do more pvc gluing to complete the access end, but shouldn't be a problem.

 

Thank you!

 

[edit] I went looking but the part seems to only be available in Australia.  Is there something similar in the US?  I tried the cleanout plug with threads and didn't have any luck.

I don't know if it's available in the US - yes it does have a gasket underneath.  I fully expect it's made in China so could end up anywhere, but it would likely depend on local plumbing codes.  You may need to look more widely for a solution if you can't find it in plumbing fittings?  Perhaps as a first step visit a local plumbing supply centre and ask for options?