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Hello and thanks for your help.

Background:

I'm working with a local high school gardening program.  Last year my coworkers and I built an aquaponic system.  This year we help the students maintain.

Water is stored in two large 100 gal reservoirs we ordered from Growers Supply: http://www.growerssupply.com/farm/supplies/prod1;gs_hydroponics-gs_... .  The tanks are connected by 1" PVC pipe to help keep the water level equal between tanks.

Problem:

Today I have begun to suspect we've sprung a leak from the bottom of one of these tanks.  I've checked the caulk around the connector pipe and all of the other plumbing, and nothing appears to be leaking.  I believe that the leak may have gone unnoticed for a few to several weeks.  We typically lose about 20 gal / week to evapotranspiration.  This week we lost ~ 25-30 gal.

Questions:

Before I leap into repairs, I wanted to ask for your advice:

  • What do you think is the best way to patch up a leak like this?  Caulk?  Something else?
  • Of course, we'll have to drain the tank to make repairs.  Because the reservoirs are connected, what would be the best way to plug up that PVC pipe?  I'd hate to have to drain both reservoirs and displace all of the fish if I don't have to.
  • Should I look into ordering a whole new tank?  It would appear that Growers Supply has discontinued or is out of stock of this specific type of reservoir.  We're also low on funds, and if there's a way to avoid this $300 purchase I'd like to explore that.
  • How long do you think this can go before we need to repair?  I'd like to get on this ASAP, but the school is about to let out for the holidays and we won't have access to the system over the break.

Thanks for your help!

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Can you see water on the floor or somewhere it shouldn't be? It seems to me a few extra gallons lost one week over another could just be difference in temps and humidity one week to the next. I don't think I would jump into repair mode until confirming you actually have a leak. My system is outside, so I guess I may be too laid back about a small leak here or there, but I do know the amount of water I lose from my system varies greatly based on the air temp.

Hi Amanda,

If you can describe the type of fittings used on the tank itself eg. bulkhead fitting, if its threaded or non threaded, size etc. Some pictures of the outside and inside if possible, will be helpful. I had a similar problem which i plugged from the inside of the tank then disconnected the outside parts, repaired them and reassembled. You might have to drain the one tank with the leak completely if it turns out to be the tank housing itself. There are many problems and numerous solutions for leaks.

Hi Daniel and Harold.  Thanks for your help.

Daniel:  The system is located inside a greenhouse where the temps are kept at 70F.  When I walked in the greenhouse yesterday morning there was a trickle of water from underneath the left tank to the drain in the center of the greenhouse.  I initially thought it was from a spill, and mopped up.  It reappeared.  You make a good point that a few gallons lost a week in a system this large isn't that big of a deal.  If it's only dribbling out about 5 gal a week, I wouldn't think that would get too much worse over the holidays.  But if it does, the consequences would be pretty dire.

Harold:  Good idea.  The PVC pipe has threaded fittings, but what makes it water-tight is layer upon layer of caulk.  Unfortunately it seems like if the pipe shifts at all, we risk pulling some of the caulk away from both tanks.  Because of the tight location of the tanks, I'm not sure I'll be able to just prop up one side of the pipe and disconnect the tank to repair.  Attached is a picture from when we were constructing this spring.

I realize now that during construction we should have put more consideration into future maintenance issues.  These reservoirs are not set up to be easily adjusted.

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Hi Amanda,

Ok. I see from the pics you have male adapters through each tank with fixed length between the two tanks. Silicone does not bond with the poly material of you tanks. Silicone should really be thought of as gasket material, to be compressed between two faces. what you will need is two of the same size or larger(larger is better to minimize slime buildup)  bulk head fittings. In the middle of the pipe joining the two BH fittings place a PVC union the size the pipe, for when you are moving/upgrading/cleaning the system, The BH fittings come in two pieces with a rubber gasket, which is placed on the outside of the tank and the fittings tightened allowing water through and not around the fitting.

Get as many containers as possible and save that precious nutrient laden water. After the repair/upgrade you can refill the tanks. You won't want to deplete your AP of these vital minerals, so the faster the better.

Thanks for your help!  Where can I get these fittings?  Home Depot or a plumbers supply?

Hi Amanda,

I am from the Caribbean and we don't have those stores here, but i went online and I see that Home Depot has them. The BH fitting has a rubber gasket so you won't necessarily need to use the silicone here.

Amanda, I've used these. They don't cost too much.

http://www.aquaticeco.com/subcategories/2986/Bulkhead-Fittings-Economy

 US PLastic also has bulkhead fittings.

 

Harold is correct about the silicone. You'd need something more like, 3M  '5200' boat caulking. If I remeber, even their 'fast cure' takes 24 hours....

Hi Amanda from Shady Valley in East TN.

I use standard TA's (threaded adapters) from Lowes. The male is from plumbing and the female from electrical (no taper so they thread all the way together.) I place an "O" ring (also from Lowes in the plumbing dept) on the female side slipped on the male before you thread on the female TA. A little marine silicone on the threads never hurts.

Didn't catch what size u are using but Lowes largest "O" ring only goes up to 1" so if bigger I would hit an Auto Supply.

Here's a pic of some parts. In this case for the top of the fish tank but same idea:

That grey TA is the one from electrical and has a very small exposed surface area even though it is not intended for potable water (no worries).

Hope this helps and if you're ever out this way come see us in the Smokys About 2 hrs from U just past Johnson City home of ETSU.

Jim Fisk said:

Hi Amanda from Shady Valley in East TN.

I use standard TA's (threaded adapters) from Lowes. The male is from plumbing and the female from electrical (no taper so they thread all the way together.) I place an "O" ring (also from Lowes in the plumbing dept) on the female side slipped on the male before you thread on the female TA. A little marine silicone on the threads never hurts.

Didn't catch what size u are using but Lowes largest "O" ring only goes up to 1" so if bigger I would hit an Auto Supply.

Aha!  Ok we do have both male and female threaded adapters in each tank connecting to the 1" PVC pipe, but neither have an O ring.  They're just caulked (alot!).  It's held without leaks for almost a year now.

And hello back from Knoxville!

David Hart said:

Harold is correct about the silicone. You'd need something more like, 3M  '5200' boat caulking. If I remeber, even their 'fast cure' takes 24 hours....

It's OK for us to just wait for 24 hours if we're able to repair.  Where have you purchased 5200 boat caulking?  A marine supply maybe?

Thanks for your help!

I don't think looking at your pic that you used an electrical TA for either the male or female thread. Either one will do in my experience. Normally I will use it for the female even though my pic showed a male but that was because my skimmer tee has a female thread. If you use 2 plumbing TAs due to the taper, you will never be able to tighten them far enough before the taper jams you up. The threads on the electrical TAs ARE NOT TAPERED. Very important. Use what I am suggesting and you will not have leaks and you will save $. Marine silicone and "O" rings are cheap. You should not need caulk.

Good deal.  I can see now that I'll heed to make some changes to the system while I'm repairing the leak.  Thanks for your assistance!  There are two more obstacles to overcome before I do this:

  1. Does anyone have any tips for finding the hole?  Based on the small amount of water lost and the trickle of water on the floor, I'd say the hole is very small and difficult to find.
  2. The sides of the water reservoirs are tapered.  I'm concerned that when I update the male/female adapters, I won't be able to connect them with a level piece of PVC.  Thoughts?  Attached is an old photo of one of the bins to help you visualize the extent of the tapering.

Thanks again for your help!

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Have fun finding that leak, A good flashlight and a dry hand is a good start.

As far as the taper is concerned I don't think it is enough that it won't conform as long as you can crank down on the TAs. Make sure the "o"ring is hard to fit on as it will pop out if it is too loose. The silicone not only helps the seal but is a great lubricant as you tighten the TAs.

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