OMG Aquatics

http://aqpkg.com/Styro-Liners.html

Try adding some Seachem Pristine. There is likely decaying waste you're not seeing in your tank.

Blue Bolt Low Grade and Blue Dreams

GH is WAY too low. Neos should have a GH of 6 - 10. Find a way to lower temps as well.

Increase the height of the spraybar or lower water volume.

Did you add ammonia into the tank for cycling? Are you using any nitrifying bacteria supplements?

Looks like it has green fungus disease as well.

http://www.chelonia.org/articles/waterchemistry.htm https://www.discobee.com/blogs/news/17030569-dwarf-shrimp-water-parameters

That looks like inert substrate? If so, that's a problem.

Would be best to just net out all shrimps into a container and do 90-100% water change. If you have a large buildup of mulm, that may be why your pH got so low.

Using limestone for GH isn't a stable method of maintaining GH. Every time you do a water change, GH will drop and the limestone will slowly increase. Also doesn't limestone increase KH? You said your pH runs at 6.5 but could be lower. If you have a KH of 2, there's likely too much waste in your tank lowering the pH. Neocaridinas don't do well under 7.0 pH

Your GH is way too low. I recommend a GH between 6-8. It's highly likely that your shrimps are dying due to unsuccessful molt from the low GH and the assassin snails are just eating the dead ones. They also prefer a pH above 7. You would need a remineralizer to increase your GH.

NY

People believe that caridinas do not move as much which results in nutrient deficiency which results in lower survival rate. Neos tend to swim all over and explore which is why their survival rate is likely higher.

About 1.5 years in 3 tanks. All substrate will break down eventually but usually will likely take years.

Try SL-Aqua Nature Soil. It keeps my pH around 5.3-5.7 for a good year and up.

Blue Bolt Shrimp - Low Grade are shipped around 0.7 - 1.0 cm. They have a blue head and white body. Water Parameters: pH : 5.5 - 6.5 Temperature : 66F - 74F KH : 0 GH : 3 - 6 5+1 for $42 10+1 for $70 USPS Priority Mail $7 - $20 USPS Express Mail $25 - $45 Insulation $2 Live Arrival Guarantee 100% Live Arrival Guarantee on EVERY order if the following conditions are met : Package must be delivered on first delivery attempt. A clear photo of unopened breather bag next to my shipping label within 2 hours of delivery confirmation must be sent to sales@omgaquatics.com If the temperature in your area is above 80F or below 30F, you will only have 1 hour to provide photo and claim Live Arrival Guarantee. We will send replacement or offer store credit/refund for the deceased shrimps/fishs/plants. Failure to do so voids Live Arrival Guarantee. PM me if interested.

Add baking soda and exhaust the substrate. Do water changes every 2-5 days and add more baking soda until fully exhausted then 90%-100% water change. Fill it up and wait a few hours. If there are ammonia readings, add biodigest. If there aren't any ammonia readings, wait until you add the neocaridina before you add biodigest.

You might have to dose again once every week for about 4 weeks because pretty sure it won't kill eggs.

If you want to maintain KH at 2 with Amazonia, you're going to have to exhaust the substrate first or it will continue to reduce to 0 until exhausted.

I use both SS GH/KH+ and SS GH+ SS GH+ for caridina shrimp and SS GH/KH+ for neocaridina shrimp I don't measure by spoon but rather by TDS. My rodi water is 0 TDS and I add enough SS GH/KH+ until it reaches 200 TDS which is roughly 8 GH and 4 KH.

http://www.theshrimptank.com/water-conditioners/salty-shrimp-shrimp-mineral-gh-kh/ Use a shrimp specific remineralizer. Changing GH does not mean changing pH and KH as well although in this case, it does. Bee shrimp remineralizer only changes GH and not KH but since you're keeping neos, a GH/KH solution is better to prevent pH swings.

Remineralizers consist of pretty much just Ca and Mg. I've had the SS GH/KH+ tested for Ca and Mg and the values are almost exact same as the ones given on the Australian forum. As far as what else is added, I'm not interested in cashing out big money just for a water test to get the exact formula. I've been using my own formula for quite some time now since I'm running low on SS GH/KH+ and so far have not seen any color issues or molting issues.

No one knows the exact formula. Testing can only give us estimates of which minerals being used to create the remineralizer. Pretty sure no pet shop in the US offers testing to find the exact minerals. It's just pH, GH, KH, ammonia, nitrite, and nitrate.

Buy SS GH/KH+. Use it in rodi water and get the water tested?