possible stupid question (TDS)

[gnomey]

If i know that the gh/kh of my local grocery stores RO water is gh 2 drops (35.8ppm)and kh 1 drop(17.9ppm), ph 6.0, can i pretty much figure that the TDS is low? or do i need to purchase a TDS tester?

i'm trying to (very) gradually switch my tank over to 40-50% RO as recommended by a nearby local blue ram breeder. my tap water is pretty high, gh 11 drops and kh 13, ph of 8.0

i tested mixing straight tap with 50% RO and got gh 5 drops, kh 6-7 drops, and ph 6.5

thanks ahead of time for enlightening me!

[mrkookm]

If i know that the gh/kh of my local grocery stores RO water is gh 2 drops (35.8ppm)and kh 1 drop(17.9ppm), ph 6.0, can i pretty much figure that the TDS is low?

That assumption is correct due to fact that it's RO we are talking about here but it's not necessarily true for every situation. TDS is affected by anything that goes into the water so a meter is the way to go if you're looking to maintain a range over time.