Waterproofing LED power cable

Wasn't sure where to ask this so I placed it here. I have a 250mm reservoir (EK-MultiOption RES X2 - 250 Advanced) and with its current configuration, I can only place LED plugs and LEDs at the top which doesn't do anything to light up the water. So, I tried Logisys 9 LED Flexible Water-Proof LED Strip at the bottom which worked great but it wasn't so waterproof as it claims. Started deteriorating after 5-6 days. I know have BitFenix Alchemy Aqua LED strip which I'm told but Bitfenix is totally guaranteed to be water proof and has been tested.

The problem lies in the length of the power cable. The power cable to this LED strip has its connection about 4ins from the strip. This is where the connection is made between the 3pin and to its molex adapters. After placing the LED strip at the bottom of the reservoir, the power cable's 3pin connectors (male/female) will still be inside the res with about 3-4ins before reach the top. My question is if I remove the connector and splice with a section of wire is there a way I make the spliced area waterproof?

heat shrink "should" become waterproof if its small enough to cover the wire.. do 1 wire at a time. Beyond that you'd need like liquid rubber (which benchers use often) to coat everything up.. dont know if i'd trust it under heated water for extended periods of time though..

I'm not sure I'd trust heatshrink either; it's not really designed for that. What about a nice big blob of hot glue?

Adhesive lined heatshrink is made for this. You really need to use a real heat gun for it though, not just a hair dryer or Bic lighter.

If the strips didn't get hot when running out of water, I'd be tempted just to tape the strip to the outside of the reservoir. Maybe some nice shiny aluminum furnace tape with the peel off paper backing..

I've seen a few things about using silicone sealant and then covered with heat shrink. But waterproof doesn't seem to be the same as submerged for extended period of time waterproof. Not sure about the glue either. It may work but just can't see having a blob of glue floating in my reservoir. lol Just not understanding how a company can make a supposed waterproof LED light string with a 4inch power wire before its first connection. I'm probably FUBAR on this one. It's the only remain task to solve before installing my water cooling components.

You can try emailing them. If they make their own they should be able to get one with a 12" lead just as easily.

I've used the silicone in the heatshrink method myself, but I have a blunt needle syringe made to apply the sealant nicely down inside the sleeve before shrinking it.
As for a sealant to use, Marine Goop is hands down my favorite. It lasts for years underwater without fail. (Lowe's/Home Depot/Ace)

Another idea I just remembered.
Stretch the wires evenly 1/8" apart with the solder joints across a piece of wax paper and tape them down. Apply a neat bead of Marine Goop and let dry. Turn over and apply a bead to the back.
You can trim the edges with a razor knife once it's all cured overnight.

Not as purty as heatshrink, but it works well with low voltage. Heatshrink it afterward to dress it up.

^ Yup. Exactly the same idea as hot glue. Marine Goop is good stuff.

One layer of liquid electrical tape, then some heatshrink on each wire, then a little bit of silicone at the end of that heatshrink, and then another layer of heatshrink over everything to tidy it up

Silicone if applied correctly is completely waterproof. I have resealed enough fish tanks to prove that.

Glue lined heatshrink is an alternative but you have to have the correct size and heat or you just made a glue filled tube for the water.

Goop/Marine Goop/Hot glue WILL work but again, if applied incorrectly, you just made a delayed sparkleparty.

Yea, I think the makers of the first LED string did shotty work on encasing the LEDs and cabling on the bottom. I think I'll try and add some silicone to those first before looking at the second set of lights. The second was suppose to be a relatively short 6 LED string but it isn't so I may have no use for it inside the res. The string is about 7-8 inches and no way I could place it the way I wanted.

Let me ask about the Marine Goop stuff. If I applied it to the first LED string I have to beef up the silicone encasement, will the goop work in that manor as reinforcement inside the reservoir?

Goop bonds well, and does dry harder than silicone, but I wouldn't call it a reinforcement.
Using the LED strip as a reinforcement by attaching with Goop?...I would say both are too flexible to stop it from being crushed, but it may slow/stop a crack from propagating.

Think of it as being similar to rubber cement, only clear and faster drying.


BTW, found it at Dollar General this week. No idea how far spread that store chain is though...

Well, what I was talking about was adding a layer of marine goop to the base of the LED string I have reinforcing the base where it seems that it's lacking in thickness. There aren't any cracks in the casing. This is a new light string.

Gotcha. Yeah that should work good for that.