Walmart has Instant Power Septic Shock for $6.42 with Free Ship to Store or $35 order. This is a good price since it’s normally 10 dollars on up. It has good reviews and I’ve used it myself.
https://www.walmart.com/ip/2L-Fre…k/38691830
Amazon also has Instant Power Septic Shock for $6.42 with Free Ship with Prime or $49 order.
https://www.amazon.com/Instant-Po…ptic+shock