Surging generally indicates a water shortage or suction problem. There are four possible issues for surging jets:

1. Low water level - top up your water, and check inside your spa to see if there is water inside. A low water level commonly results from heavy use (evaporation, splashing, brought out on skin and suits) but may indicate a leak.
2. A sticking filter weir. We introduced an adjustable weir basket some time ago, which has been included on all spas produced after Jan, 2006. If your spa was made before that time, you might ask your dealer for a replacement (this is NOT a warranty item). If your spa was made after that time, check the adjustment of the black ring at the bottom.
3. Clogged filter cartridges (easy to check and fix)
4. Partial airlock in a pump. Reprime - See below

"The jet pump, heating system and all internal plumbing will achieve a partial prime as the spa is filled. To check the operation of the jet system and to remove any remaining air from the heating system, push the JETS button twice (for Signature series spas, push both JETS 1 and JETS 2 buttons; for Legend series spas also push JETS3) to make the jet pump(s) run on high speed for one minute. Once the jet system is fully operational (as indicated by strong, non-surging jets), priming of the spa is complete. Weak or surging jets are an indication of a low water level condition or clogged filter cartridges."