ppm confusion

I got one of those aquarium test strips and it gives PPM readings for total alkalinity, total hardness, nitrite, and nitrate (it also gives pH but i have a digital meter for that and adjust this accordingly).

Anyway I keep reading that above 200-250 ppm one should use distilled water, or RO, etc. But 250-250 ppms for what category? Hardness? Alkalinity? Nitrite? Nitrate?

The strips showed my tap water's total hardness to be between 25 and 75 ppms, and my alkalinity around 40 ppms. I could not decipher the nitrate and nitrite readings because the strip colors go from white, to light pink, to hot pink (as ppms increase), but my readings for these were dark gray and light gray, respectively.

Are these strips useless? If not, are my readings within range or should I use distilled water?

Thanks in advance to anyone who helps. Truly appreciate it.

I wouldn't rely on them. If you just need to know the characteristics of your water your water company will tell you that. If you need more you should get a ppm meter, a good one can be had for about $55

If you get the right strips an can read them they will be more reliable than any almost any meter under $100 will ever be.

strips are not as reliable as color liquid kits, but those have a problem as well, nutrients tint the water changing the color. I say get a good tds/ec meter and be done with it. i bought a waterproof HM DIGITAL tds/ec/temp meter for 68 dollars. It's come in really handy with my tomatoes and peppers.

The other tests are helpful in aquariums, but not as useful to gardeners. the main things to check on a hydro setup are PH and TDS (ppm) or EC.. Its best to start with the cleanest water you can get. Tap water can be used but distilled or ro/di is better. I start with zero ppm water, just makes the math so much easier. I make 5 gallons of water at a time and just adjust the PH accordingly.

I'm not dissing anyone's opinions, just giving mine.


JP