EC and ppm are different measures of the same thing. Electrical conductivity of the water from the total dissolved solids or TDS. The mineral salts that plants feed on allow current to flow between the two probes on an EC/ppm pen and give you a measurement expressed as EC or ppm. Different makers use different conversion factors to express EC as ppm so a lot of guys will say that EC is the only way to go but if you know how it works they are all translatable.
With DWC I'd start clones at 300ppm or 0.6EC. Knowing the EC/ppm of your nutrient sol'n is one of the most important things to know about feeding your plants in hydro and a decent pen can be had for around $20. Around $10 more for a liter of 1000ppm calibration sol'n to make sure it's on the mark. That lasts for a long time.
This can be printed out for reference. I use ppm pens that convert EC using the Hanna scale. My 20 yo old one that still works is actually a Hanna.
A pH pen is another needed tool when growing hydro. Cost a bit more for a decent one and you should have 3 sol'ns. pH 4 and 7 calibration sol'ns and some storage sol'n to keep the probe sitting in when the pen is not in use. A squirt bottle of clean water should be handy to rince the probe of between uses as well.
I rarely used my pH pen after the pH Perfect nutes came out. With RO water I never bothered checking any more and never saw issues from the pH being out of whack. The last 20 or so DWC grows out of 50 I've done never got checked without problems. Most never got a change of nutes the whole grow either. Just monitored the ppm and made adjustments as needed to keep the ppm where I wanted it.
Two of those CFLs aren't going to get you much pot and you need to get then as close as 2" from the leaves to get any decent growth at all. That plant is all stretched out from lack of decent light and reaching to get some. When I use CFLs to veg small plants I attach tin foil right to the backs of the bulbs to get maximum light on the plants and have them almost touching the leaves. A few scorch burns here and there won't hurt nothing and the leaf has to be in contact for an hour before starting to dry out and it starts slow. At the height they are now is where I would have my 400W MH at. It'll fry leaves in 5 min at 4" away.
You probably won't want to do it but I'd cut that plant back to the lower set of fan leaves. Clone the top you cut off for another plant. Get the CFLs in close and you'll soon have two new grow tips coming out at the node. The cutting could sit right by that plant and share it's light.
You're going to need better lighting if you want any pot besides a few wispy buds. Lots of deals on Amazon etc for lighting kits of all kinds. LED is the big deal these days but hard on the wallet for something decent and I know very little about them. I use HIDs for all my growing past seedling stage. 400 or 1000W bulbs of decent quality like Hortilux. My grow room is in a very chilly basement so I need the heat those lights give off.
Plants grow better with a period of rest just like us so most experienced growers use a 18/6 lighting schedule. When growing autos 24 hours is good to keep them growing longer before they automatically start to flower then they and their yields get bigger. Once they get into full bloom then 18/6 or 20/4 works fine.
What are you using for nutes? Maybe I can help you figure out how much to use to get a good ppm without buying a pen right away.
Lots to read in this link.
I found a great spot to download
FREE POT BOOKS. I downloaded a grow bible first and got lots more. Books look great and complete like the real ones I have here. No web site but just a page of links. Just right click on what you want and then "Save Link As" to download so they don't open first as some are 50+ megs. They got lots. Enjoy.
Can anyone shoot me some advice on my system, 250 watt lights, one pump two air stones lots of oxygen, remo nutrients once a week, netting pots are one inch off water, I'm not getting a lot of growth and leaves are starting to curl and brown and yellow in spots not around the edges though, I'll add some pictures, roots aren't bright white kinda light brown, I did have light creeping into the reservoir but as of yesterday I have fixed that problem, I just don't want this one to die I already lost 4 she is my last haha also on a 24 hour light cycle right now
