TDS and EC are both measurements of water hardness/fertilizer content. TDS means 'total dissolved solids' and EC is 'electrical conductivity'.

pH is the concentration and action of hydronium ions.

If you are growing in soil, all you need is GOOD SOIL, and a $7 bottle of liquid pH indicator. You get into meters when you go hydro, or scale up to a large soil grow.
stinkyattic Reviewed by stinkyattic on . SO CONFUSED! which meters do i absolutely NEED? OK so as i understand it ec meter measures how hard/soft you water is, tds measures nutes in water and ph measures ph obviously, but which are absolutely needed? im doing my first grow and want to try to save some money. ill be using fox farm 3 part nutes, Can I just use ph paper to test water before i water plants (with nutes in water) and adjust it and then test runoff for soil ph? And just buy a tds meter later if i have plant problems and forget about an ec meter? Rating: 5