Fish recommendation for 40 liters aquarium

[Ghraise]

Because 1 °fH = 10 ppm, 1 ppm = 0.1 °fH

The chart is confusing. Going across the chart, one side it says 1FH = 0.1ppm but going down it says 1FH = 10ppm

When I did 50 x 1.785 (the dGH number) it came up with 89.25ppm

I'm confused

Because 1 °fH = 10 ppm, 1 ppm = 0.1 °fH

 

[MattW]

I don't know much about water parameters but could mixing tap with rain water instead of RO for example also bring down hardness?

 

[Essjay]

In the chart, read across the top line to find 1 deg F. Then go down the column to find the equivalent in the other units. Down from 1 deg F we have 0.09991 mmol/l; 10 ppm, 0.5603 dH etc.


Or use this calculator

Hardness of water, Cactus2000

Online conversion of the hardness of water into a number of international units.

www.cactus2000.de

and enter 50 in the deg fH box

 

[Ghraise]

I don't know much about water parameters but could mixing tap with rain water instead of RO for example also bring down hardness?

Rainwater is typically noted to have 20 ppm. If the hardness of your water is above 20 ppm, it will reduce the hardness, but since the pH of rainwater is in the range of 5-6, it can negatively affect the fish in the aquarium.