Dwc newbie - a little advice, please!

I am about 4 weeks in on my first grow (I have two female white widows from feminized seeds and five from unknown/free seeds). I'm doing a closet grow and I have a T5 4' blue spectrum light with red spectrum bulbs for flowering later. My plants look great, but every time I change out the water/nute solution in the buckets, the ppm's and pH keep going way up (even though I am putting the same amount of nutes)! I'm checking them twice a day now, and I'm always putting in pH down. Once you put your nutes, you balance the pH, right? I have a pH testing pen and a ppm meter. Does anyone have a clue what's going on, or it this normal? I'm trying to take the best care I can of my pretty babies!

Are you doing dwc your very first grow?

Yes, I'm doing DWC even though I'm a newbie! Got lots of helpful advice from others, as well as on this forum. So far everything is going great and they look beautiful; I just put them in flower yesterday. I'm hoping soon I can tell if the free/mystery seeds plants are males. DWC is a pain in the ass, I have found out, works great, but still a pain!

Sounds a bit early for flowering (depending on when you considered their first week of life) and just one light fixture? For florescence , you want some more light unless you want small plants and your training them or something.. But more light never hurts.. As far as your ppms and ph.. You seem to be getting your own thing down, so I assume you know the levels you need.. Ok, here's the deal with the fluctuations.. You gotta understand that tds means total dissolved solids and just think of that as salt for now.. When you mix your nutes (salts) with water, your mixing them to come together, but microscopically, they aren't all one molecule.. You just have a mixed up batch of different molecules combined with the water.. Let me get a little lamen's terms with the point I'm tryina get.. Do you remember in science lab back in middle school when your teacher made you mix some salt with some water and you let the water evaporate to separate the water from the salt? Well this is the same kind of thing happening to your dwc set up.. As water evaporates, your ppms are gonna go up.. Because the original water to nutes(salts) ratio is become different (losing water) so it'll seem like your getting more nutrients some how.. Crazy right? But there's more than one way to get higher nutrient level readings.. One, by adding nutrients to your water solution.. OR.. Losing water (which doesn't take nutes into the air with the evaporation) causing readings to seem higher. That's what's happening with the tds/ppm fluctuation.. As far as ph goes, not so sure.. You should get a gradual change by like.. .2-.5 from the beginning of the week to the end? Maybe.. Just depends on everything lol. It depends on the ph pen you've got (weather it's a cheap $5 one or a fancy accurate one) and make sure your using it properly and storing it properly as well.. Make sure you calibrate it correctly (every time before use) and keep it clean in between uses.. When you make a new solution, depending on your res container, you should make it before you dump the old one so that you have time to get everything right and not being rushed and worried about the roots drying up.. Like if your using a 5gal bucket, have 2 for each plant! So that the lid holding the plant can just be swapped onto the new one.. When you make your baby juice, make sure that you take your time and mix it well between adding different nutrients (just take it slow with one at a time) because it's not good to mix them un diluted. When you take a ph reading, take one after you mix it up, and before adjusting, mix it again and give it 5 mins.. You'll see that it "usually" isn't the same as 5 mins ago.. Cause the chems need time to react and do their thing and then they end up changing chemical properties and what not, leaving different ph readings.. I usually check my ph, wait 5 mins, check, and wait again before checking again.. Just to get an idea of which way it's going and then ill adjust.. Also, everyone says that there's a perfect ph level, but just try to get it somewhat close.. Don't be too anal about being spot on, or you'll end up putting too much of that ph up/down which can hurt the plants if you put too damn much.. There's allot more factors to everything I said, such as the dependence of what water your using, what nutrients your using, the loss of water through roots, (as well as nutrients) and temperatures and what not.. But this should shed a little light on things.. Just try not to adjust the ph every day! Let them change a little bit, but not like past so much.. It's always better to do a nute change instead of trying to adjust yours too much! Also, when the ppms get higher from loss of water, just add some ph adjusted water until you get the desired ppm level your looking for.. Hope I could help! Good luck to you and grow on

Thanks so much for all the info! You're absolutely right - adjusting the pH so often was raising the ppm's like crazy! I'm in the process of getting a good handle on what to expect as far as pH, ppm's, etc. go. As far as how old my plants are, do you start counting from Day One - seed, or do you start counting once you put them under the lights? Mine are actually 8 weeks old if you count the germinating stage. But the free/mystery plants are very tall (18"-24"); the white widows are short and bushy (12"-14"). If they double in height (which is what I have read), then I had to put them into flower because they were getting so tall! Speaking of tall.... I'm thinking the mystery plants must be males based on the fact that they are so tall, there's so much space between nodes, etc. But I guess I'll find out for sure in a couple of weeks.

Another question: I have looked at lots of pictures of plants where there are no branches or leaves on the bottom - just a main stalk and branches with colas. Should I be trimming away any of the leaves during flowering so that the tops on the lower portion of the plant can get light, or do you do that just before harvest/cure? Hope this is not a totally stupid question - I know some people say don't ever trim any leaves; others say trim away. Just wondering.

Also, just to let you know, I just bought a 600w HPS light to use during flowering. It hasn't arrived yet, but as soon as it does, I am going to replace the T5. I plan to use the T5 for vegging and I'll use the HPS for flowering. I'm hoping to get a system going where I have plants in both veg and flower in different areas in my grow room.

Good idea with the alternate stage system. If you do it right, you can have harvests every 2 months! As far as your question goes, cutting the plants lower leafs is usually something that people do when they are worried about not supplying enough light.. Such as scrog methods and such.. Really only when necessary (such as when the plant isn't getting any light to those leafs absolutely at all and is considered a waste of the plants life's energy) if you post some pictures, I'm sure you can start a thread asking advanced growers opinions if necessary or not. But doing so is very stressful for the plant, can, and usually does stunt plant growth.. If you do decide to do it, make sure your ridding the bigger fan leafs first (so I've read) and also to start with just half the leaf and then take the rest anther day to reduce stress. As far as the sexing, I wouldn't rely heavily on the height as a method to determine sex.. That's usually somewhat reliable when your growing lots of the same strain. Because the genetics are different with different strains, that's why you widows are kinda bushy, prob not because you've done anything wrong, but because they are that way! And the other plants your growing can possibly be more indica dominant and that would make them grow leggy like your describing. Also leggy growth could be coming from light not being close enough! Seeing as it seems the way you describe, in your context, you have one t5 light for that many plants? You may want more than just one bulb going depending on how many lumens per square foot your getting and what not.. For my vegging, I start seeds/clones with a cfl low wattage (like 20-30w) and as they get bigger I add more (up to like 10-20 per plant) usually I don't do that many because how much that would cost! What I do, is once they get big enough I just throw my hps on them 24/0 (which is usually close enough to flowering that it's not too bad) let me know how things turn out!

"Sounds a bit early for flowering"

I veg for 15-20 from seed! Why is 4 weeks to short? If i let them go longer they get way too tall for my room and it 8' high. Veg time is totally arbitrary!
Also try lowering your TDS at the start of refill and see if that helps to stabilize the PH.
What levels are u running re ph and tds?
I have found with my setup that the ph will rise slowly but as the draws near for a res change the PH will actually start to drop.
As far as pruning the lower foliage again i think that is an arbitrary practice with many differing opinions. I dont prune myself but do some LST. Keep reading and try to decide what is best for you. Use the generally accepted practices and tweek them to suit your plants.