Best cleaning trick for a Protank (and the salvation of your vocal cords) is to ditch silica. That...keeps it clean. No useful purpose on this earth for such a creature as sili-ca-ca but to call it a wick. I think we've all been had. The gurgling sound you all are hearing is the result of disturbed airflow created by fragmenting silica rope. The more you vape the more you hear it. Ignore it = flood. Use cotton, Nextel or Ekowool in that order if you want a decent vape on a Kanger.
If I was a conspiracy theorist I'd swear they invented silica as the Trojan Horse to doom this industry to regulation, at the end of the day. Fortunately wiser individuals, actual consumers, have had the wherewithal to go against the grain of convention and, daresay, "risk" alternatives like cotton and ceramic.
Best vape I've experienced thus far came this evening with four uninterrupted hours on a very slowly draining tank using XC-116 Nextel on a 1.75 mm i.d. 30g 8/7 coil @ ~ 2.2Ω, 7.5W (zMax, eVic, N-Zonic, fresh Panasonic, Samsung, AW) with a prior used and washed smidgeon as a flavor wick. To look at the crimped assembly you'd think it would never wick.
Well the tank's about empty and I haven't discolored a thing. Nor is there a leak in sight.
Hit it hard, hit it long, hit it often, low power or hi, Nextel tastes great, less filling.
Good luck all!