That tingling feeling you’re experiencing is almost certainly a grounding issue rather than a problem with the pumps themselves. Even with GFI outlets, concrete floors can allow stray voltage to build up, and any metal equipment or wiring that isn’t properly bonded to a single ground point can create exactly what you’re feeling. Installing a grounding probe and making sure all pumps, filters, and other electronics share the same properly grounded connection usually resolves this. I’ve seen it happen even with high-quality pumps, including the Best Pond Pumps From MidWest Ponds, and once everything was tied to a dedicated ground, the shocks stopped completely until then, it’s safest to avoid touching the water with open cuts.