Need advice for sudden colony deaths
Hello plantedtank! I’m a long time lurker but this is my first time posting.
I have been keeping a small colony of PRLs for about 8-9 months, I started with five from a breeder and slowly got my numbers to about 20 (my breeding rate is another problem entirely) and recently I’ve experienced a problem that seems to be getting worse as time goes on.
My parameters for my tank are as followed:
GH: 6-7 (hard to tell from test)
KH: 0-1 (hard to tell from test)
Substrate: fluval stratum
Other tank mates: chili rasboras
Tank size: 5.5 gallon
RO DI + salty shrimp GH
The first thing I noticed is GH seems a bit high with the corresponding TDS my meter has always been consistent so I’m not sure if those values normally correspond to each other.
About two weeks ago I had 4 berried PRLs that had eggs hatch, during routine maintenance I trimmed my plants and ended up disturbing the substrate a bit while removing some over growth. Topped off evaporation with RO DI and called it a day. A few days later I added some dwarf hair grass I purchased online from a seller I have purchased from before, I immediately noticed the PRLs avoiding the area with the dwarf hair grass except maybe one or two of them going over there to explore. At some point last week I had one death, cannot confirm if it was molt related, shrimp looked intact. The following day I found another death and a sluggish shrimp, that shrimp died later that day, the remaining shrimp were acting normally. Around this point in time I realized all of my babies seemed to be gone. I began to suspect the dwarf hair grass and promptly removed it, covered the bare area with clippings from the tank from other plants in there. Shrimp were acting normal, eating, doing their thing after dwarf hair grass removal. This morning I found my eldest male dead and second dead shrimp. All the deaths besides the eldest male (who was probably about a year and a half old, one of my starter shrimp from a breeder) were adults who were born beginning of September. I noticed also this morning a large amount of molts in the tank that looked about the size of the shrimp who were all born during the beginning of September.
I’m beginning to think that I am having molting issues and that it corresponds to my GH being higher than it should be compared to TDS? Naturally adding more RO DI would be the answer but I’m concerned because my TDS is already so low that it could make things worse. Any advice from my fellow shrimp keepers? I’m extremely saddened by the deaths and want to save the remaining shrimp in my tank.