We do carry InVade SeptiTreat which is designed to be used in septic systems to reduce organic buildup that would create harborage for drain flies. Per the product label:
Simply pour one 8 oz bottle of SeptiTreat into the toilet and flush. SeptiTreat may also be poured down a drain, followed by about a gallon of water. Results are best if applied at a time of low flow. One treatment is adequate for a typical household on a quarterly basis. For large homes with higher than average throughput, or for use in other types of buildings, two or more 8 oz bottles may be needed per quarter
Per the manufacturer Invade SeptiTreat has a shelf life of 2 years if stored in a temperature stable environment.
