I'm still researching. Notice that Hygrozyme is not listed as a substitute.
Hydroguard Bio Fungicide
Hydroguard, by Botanicare, contains a mixture of beneficial bacteria that helps protect your plant's rootsystem from root rot when growing with hydroponics.
It forms a barrier that doesn't allow the bad bacteria to infect the roots. Unlike the use of fungicides alone, the use of Hydroguard breaks the chronic disease cycle while leaving no toxic residues.
Hydroguard is especially effective when used with seedlings or cuttings in clone machines, or trays. Best when used right after planting seeds or taking cuttings.
Use Hydroguard up to 1 Tablespoon per gallon to your reservoir. Hydroguard also works well in soil.
Hydroguard Bio Fungicide contains:
Bacillus subtilis
Paenibacillus polymxa
Bacillus circulans
Bacillus amyloliquefaciens
Hydroguard Bio Fungicide is temporarily unavailable pending Department of Agriculture re-approval.
Consider these alternative root system stimulants that help increase the ability to fight off harmful bacteria or root rot: