1st grow (DWC/CFL)

Yes, you can lower your light schedule. The girls still seem quite small, I would keep it on 24/7 for another week.

Good luck with your grow.

 

I would give it a week then go straight to 18/6.

 

What PPM is you're tap water? Are you using any nutrients yet?

Get a strong fan on them, and the stems will thicken as it grows. It's not too stretched, and they look healthy, so don't panic.

 

Not to worry, bro. 365 PPM is high, and can give you problems, but I've done all of my grows so far using 300PPM tap. What I've learned from growing with tap is that those 365 PPMs have no nutritional value for plants, so you should disregard 365 PPM from you're readings. You're reading now, for instance, is 450 PPM, with only 85 PPM of useable nutrients.

The yellowing you see is you're plant's way of telling you that they're hungry. Nitrogen, specifically, is what the little seedlings are after. Nitrogen produces chlorophyll, giving the plant it's green color. No nitrogen, no green.

pH is a funny thing... It's an art, that even I havn't begun to fully understand. pH is only as stable as the amount of 'buffers' that are in the solution being tested. pH buffers are the nutrients that you put in you're water, for example, a 000PPM solution is very unstable and can change pH with a drop of two of pH solution, whereas a 1000PPM solution is quite stable, and can take a larger quantity of Up or Down to adjust it's pH. Now, not all buffers are the same, the 365 PPM coming out of you're tap, for instance, has very little buffering capabilities.

I'd suggest starting a new batch of water, just to start with a clean slate. Add whatever you're nutrient's bottle (or on the manufacturer website) tells you to add for seedlings and young plants. Most likely, this will be around 300 PPM of nutrients, on top of the tap.

Because the you're solution still has very few buffering capabilities, it will still be a task to check and maintain pH. Things will get easier as the plants can accept higher levels of nutes.

Remember to just add a tiny bit of pH down at a time, wait a while, and check again. I usually space my pHing out over the course of a whole day, making minor changes as needed.

Hope this helps, and doesn't confuse you more. It's complicated business, welcome to the wonderful world of hydro!

 

A couple things (I have tried something similar to this before and I ran into some problems like yours):

The tap water is FAR too hard, if you plan on using this water--which I wouldn't recommend--you would need to purchase a special "hard water" version of whatever nutrients you can find. This is bad because
a)it severely limits your choice of nutrients
b)the hardness comes from minerals in your water--from the pipes or from the source--of which a significant amount is calcium. While Ca is important for cell structure and the plant's uptake and use of nitrogen, it also binds to other elements of your nutrient to "lock" them out or make them unusable to the plant. You'll end up having plants look more and more deficient no matter how strong you make the sauce.
c)it takes up valuable PPM "allowance" you could otherwise use for real nutrients

DWC [H] issues:
This gave me big problems. It was the first system I used to grow (DIY project) and I couldn't wait to build a different one. It seemed no matter what I did, the pH always drifted up and fast at that. I found myself constantly adjusting the nutrients and trying to figure out why my plants looked sick even though I kept increasing the nutrients. Goes to the lock out issue again, only this time as a result of pH. Nutrients are available for uptake at in a particular range of pH and it's a constant juggling act to keep things in check. You'll want a 5.8-6.2 range. Take a look at the chart at the bottom.
Part of this could be the hard water you're using.


My Suggestions:

It's not very cost effective to purchase 10 gal of distilled water--not to mention a pain in the butt--each time you need to replace your water. I bought a "small boy" filtration system for around $90 and received the added bonus of removing the chlorine and the dissolved minerals in all my water. It's slow at 1 GPM but it does the job and allows me to use compost tea as well.

The rule in mixing sauce should always be "less is more"; however, don't mistake this for a need to underfeed but more as a need to keep it simple. Start with the basic three or two part nutrient and keep it there until you're familiar with the plants' response BEFORE adding supplements and the lot. When you start mixing nutes make sure to start low and build your way up.

Get that water taken care of somehow, and start feeding your babies! They're hungry.

PS Also a photo of my first system. Each plant was a mini-dwc made from 1gal jugs painted black.

 

glad to hear!

Those water machines outside grocery stores usually sell 000ppm R/O water for about $0.25 per gallon. if you can get your hands on a couple 5 gallon water bottles, those machines are usually the cheapest way to buy good water.