TDFrank

These are the RO results.

Yes

These are tank readings I took.

The RO membrane removes not only harmful pollutants but also a few helpful minerals. As a result, a standard 5 stage RO system produces slightly acidic water with a pH of 7. 0 or below. Alkaline mineral filter produces alkaline water with restored healthy minerals such as natural calcium, magnesium, and potassium ions, which ph.-balances the RO water

That’s an interesting idea worth looking at closer. All of my long term fish including fry born in the tank do well but I lost 5 new mollies almost over night. That’s what started this research. Thanks for the idea.

After the purifying but before the UV light is a “filter like” cartridge that adds basic minerals to the water. (red label in image) I checked and all it adds is fish safe. That was one of the first things we checked thru the fish store. I still keep an eye on it but it rarely needs attention. The tank is heavy planted and so I add some thing back with easy green.

That I did not check but being RO I suspect mine is lower than the store by a fair amount.

Thanks for the replies. I think I may have confused the issue. If I plop and drop the new fish will all die. If I drip acclimate they live much better. I am only 10 minutes from my aquarium shop where I buy fish. I have checked the water in the bag and my tank when adding and GH is the only significant difference and we are talking low hard from store to low medium hardness in my tank. There is no indication of ammonia in either and I acclimate about 45 minutes. The store ran every test known to man on my water in the tank and the RO. They were completely stumped. I’m just wondering if anyone else has trouble acclimating fiat between different KH and if I am maybe missing something else.

I have 55 and 10 gallon tanks. I found my well water had high nitrates around 45 so installed an RO system for all the drinking water and the auto tank refill. My RO system also remineralizes before it goes to the tanks. Now my GH is below that of the local fish store. The rest of the parameters including PH are OK. I find I need to drip acclimate any fish rather than just plop and drop or they all die. curious to know why the GH would be so rough on fish or am I missing something?