troubleshooting CO2 issue

here is my setup: 4 month old Keg Connection dual body regulator, 1 corny keg, 1 sankey tap for commercial keg, 5 lb CO2 tank, 2 perlick faucets with 5 ft of beer line. so i got all this set up in august in my kegerator and got it working perfectly running both kegs at around 10 PSI. the first CO2 tank lasted through about 4, 5 gal kegs. i have checked for leaks at all connections with star san and see no bubbles. i thought that 4 kegs was a little low for a 5 lb cylinder from what i have read but i thought maybe the tank just wasnt filled properly. once the tank ran out i went and swapped for a new one. i have had this one hooked up for 3 weeks. i know the high pressure guage isnt something to really go by but i noticed from the first tank that it normally hangs at the 500 mark just above the red "order gas" section. it did the same when i hooked this one up. well last week i noticed both kegs started pouring really foamy and that has never happened, so i checked for leaks again and nothing. last night i go to pour a beer and it is 80% foam. i look at the tank and the high pressure guage is pegged down to the empty mark and the two guages on my kegs had creeped up to around 18 psi, and i had them set at 10psi. i tried adjusting them back down to 10 psi and it would stay for a second then start creeping up. i noticed the packing nut was loose on each one so i reset to 10psi and then tightened the nut. i bled some pressure off of each keg and they then held at 10psi. i checked it this morning and they are still holding at 10psi but the high pressure guage is at empty. the tank feels a little light but it is hard to tell with the regulator attached. i tested for leaks and still nothing. what would cause the pressure to creep up on each keg like that? could it be that the packing nut was loose even though the set screw position didnt appear to have changed? what else could i do to check for leaks? my corny keg only has about 5 beers left in it and my commercial slim keg is about 3/4 full if that makes any difference. thanks for any assistance

Many/most regulators are such that when the inlet pressure drops significantly, the outlet pressure rises. So when you get really low on gas, the low-side pressure should start to rise and you'll need to monitor/adjust it. I have NEVER tightened that locknut on the adjustment shaft and don't experience any creep (unless the tank gets low).

The high pressure gage is greatly affected by the temperature of the tank/gas. Colder temps = lower pressure. The high pressure gage on a CO2 tank isn't a very good indicator of how much CO2 you have. It should stay within a certain range (based on temp) and then all of the sudden drop to nothing pretty quickly (based on the fact that you ran out of gas).

5' of beer line isn't quite enough ime. I would use at least double that, I typ use ~12' for each Perlick. You can always 'make' foam by just barely cracking open the faucet and letting it 'spray' but if it already comes out all foam you're kinda screwed. For now, just vent the kegs before pouring and leave them just barely pressurized and the carbonation will drop back to normal levels (over time). Get more gas and monitor the low-side gage when you start to get low on gas. Get in the habit of looking at the gage everytime you pull a beer (edit: if the tank is inside the keezer then this isn't practical, mine is outside so it sees large-ish temp swings but is easy to monitor).

5' of line has never been a problem for me. i have run 5 kegs through the system and never had a foaming issue. since this tank has only been hooked up for 3 weeks there has got to be a leak somewhere. the cold CO2 tank when full has always shown about the same reading on the high pressure guage. so if you are saying the fact that the keg pressures both creeped up and the high pressure gauge bottomed out, i would assume the tank is almost empty. how often should the nylon washer between the tank and regulator be replaced? this is only the second tank i have run and i inspected the washer when i swapped them out and it appeared fine. i have tested for leaks everywhere i can think of. i suspect though it has something to do with my corny keg cause i didnt start having these issues until i started running homebrew. i ran 3 commercial kegs with no drops in CO2 until i hooked up the corny. i have checked all the regulator connections, and the in and out connections on the kegs along with the keg lid on the corny. is there anywhere else i can check cause there is obviously a leak somewhere.

is there any downside to pressurizing then disconnecting the corny keg and then submersing it in a bathtub full of water to check for leaks? i have pretty much determined it has to be the keg leaking cause the connections seem to be fine.

You need for the fittings/lid at the top to have gas pressure contacting them and if you lay a full keg in a bathtub the beer will be contacting the lid/fittings. So you might not get bubbles even if there was a leak.

I would try to submerge what you can to check for leaks and try spraying Starsan solution on whatever you can't. Starsan is foamy enough that it works, spray liberally and look for bubbles forming. If you don't have Starsan make a soap/water solution and use that.

Does the keg hold pressure? If so it's prob not the keg itself (sometimes it might leak at a higher pressure and then stop leaking at a lower pressure). IME, the QD-Keg connection is one of the connections most likely to leak and it's one of the more difficult ones to verify but I can always detect it by spraying Starsan...or just by hearing it.

Replace the tank/regulator gasket everytime you get gas, the CO2 place should give you a new gasket everytime you refill. Also, periodically check/retighten this connection as it can drain a tank pretty fast. HTH and good luck.

I have the same problem... Sudden high reading on the gages, and an empty tank. Sucks.