You might have noticed, all my tanks are dirt (soil) tanks. I've only kept shrimp for 10 months in my dirt tanks, but in that time I have never had a parasitic or bacteria infection. I don't do anything special, in fact I still think I'm a shrimp newbie and made more mistakes than most, constantly overcompensating for slight changes, i.e. overdosing humic, Excel, Flourish, root tabs, upsetting dirt everywhere almost each week, forgetting to dechlorinate once or twice, got metal rust into the water column, and I rarely do water changes.
Why I use dirt:
1. I also have this theory based on the hygiene hypothesis that shrimp can be too clean (i.e. developed nation children suffer from the highest % of autoimmune diseases, because of lack of exposure to infectious agents such as parasites, bacteria, and other allergens growing up)
Dirt provides the probiotics, it's present in their natural habitats. So while raising a shrimplet in a sterile environment (clay-only or rocky substrate with UGF, UV) is probably best for its growth, it also renders the shrimplet susceptible to the slightest change in water conditions.
2. Dirt provides balance. Highly organic (and clay) based soils buffers and maintain pH balance. Soil is rich in natural humic content which detoxifies heavy metals and pollutants, including Pb, Cr, As, Zn, Cd, Cu, Hg, polyaromatic hydrocarbons, pesticides and viral particles in vivo, why many dirt tankers can use tap while their gravel+UGF counterparts can only use RO.
3. Dirt is better for plants, it's rich in nutrients and nitrates, it harbors beneficial nematodes and other microorganisms for speedy decomposition of rotting organic matter--for plants to uptake quickly. Humate in dirt increase the permeability of plant membranes, accelerate cell division.
1. Overdosed Calcium montmorilmonite (pH of 9), water raised to pH 7.4 in the next hour, and the next day returned to 7. Water cleared up over night. TDS shot up to 250 from 200, next day TDS reduced down to 202, but this may be clay is denser and settled?
2. Overdosed humic acid (pH 6), tanned water brown within hours, TDS shot up 5 (negligible), pH lowered to 6.6 within the hour. Overnight pH returned to 7, tannins visible reduced, over 3 days water returned to a clear coloration as soil absorbed the humic.
*Update: 1 week later, no shrimp casualties, not affected at all. Water is completely clear and TDS is constant.