Only if you want healthy plants...and the meter you want is an EC meter, not a ppm meter. The one i recommend is the Dipstick/Truncheon made by NZ Hydroponic. A great place to get it is below.

Here is a link that might be useful: Alabama Hydroponics

Checking your pH and salts concentration of your nutrients is analogous to checking the fluids in your car. You can get away with not doing it but it is not recommended. It's extra work and expense but gives you important information on the condition of your nutrients.

Product.....pH..............cF...........ppm
Tomato....6.0 - 6.5...20 - 50......1400 - 3500

How do I get the PPM up to 1400-3500? Just add 2x the recommended dose of the nutes for the plants? The PPM of my water is ~50, so thats a far way to go

It will make a difference how large your reservoir is to get nutrients up to correct ppm.

Start keeping a log and how much and when to add and change nutrients will become much clearer to you.

PPM and Ph are closely related so you should test and record Ph as well.

Well im doing 5 gal bubblers, and i wont have a reservoir. It is usually like a tsp or something per gallon for each nute, but since tomatoes have different needs i would have to do something liek a tbsp per gal? ...in general i would have to use more than the recommended dose

All nutrients are different, all nutrients have different mineral concentrations.

1. Go buy an EC meter

2. add nutrients

3. measure nutrient concentration

Hey there Adriana,

Thanks for the link to Alabama Hydro. I have the Quick Dip Nutrient Meter, but it reads, "442", "KCL", and "uS" (which I believe is microsiemens). I have heard that the 442 is good for testing pond water with fish and plants, and KCL is potassium chloride. I have no clue which one to use for testing my Millennium nutrients. I try to keep the blinking LED's in the middle, but peppers or tomatoes require higher levels.

Any advice from other hydro gardeners? Thanks, Jason

Sharp makes a good TDS meter that measures to 2000ppm. It is the T71 and is for sale at lots of hydro suppliers.

Most published stuff on hydro is given in ppm.

I have on that has been working fine for 5 yrs.

Here is a link that might be useful: another hydro supplier