Is is really necessary to change out the rez during the grow?

I see a lot of people dumping and replacing the water ever week or so and some that don't do it at all. I running two 15 gal sterilite tubs and am at week seven of flower and have not flushed once since I put them in there and they even vegged for like two weeks before the flip. Things seem pretty stable, the PH is stable and the EC is stable and the water is nice and clean with beautiful white roots. The only reason I'm considering a water swap is the fact that that I've noticed they are not eating as much it seems. I'd expect the see the EC drop considerably in a week but if I feed them and get the EC to 1.2 it might take them two weeks to get it down to 8 or 9...all I seem to have to do is top the rez off with tap water and the PH is right at 5.8 and the EC at 1.2 or 1.4 for a few days then I'm just topping off again. Like I said the grow seem really stable and the plants look great with fat bubs stinky the room..I've even had to tie one plant to some pvc for support because the bubs are so fat they weight the plant over. In addition to the slow EC drop I'm seeing some slight yellowing of the leaf tips and along the outer edges of the leafs on some plants but not all, I have a few to a single tote. I thought it looked like N deficiency but again the EC is at 1.2 - 1.4 depending if I've topped it off or not. It seems more like it's running a little hot at this point but I'm still new and don't know the difference between a slight N def. vs running a little hot. The yellowing is not bad but it's there. Could the water chemistry have gotten off with more of p/k and mg from the tap vs N over all this time? I'm guessing you can't always just look at the number on the meter. I'm using dynagro nutes per the bottle. The plants seem pretty dam healthy but in light of the slight yellowing I'm wondering if I'm doing them a injustice by not at least swapping out half the water once!

To answer your question, no. You dont have to swap out the water. But if the plant doesnt eat as much of one macro, say K, then you end up with an ec of 1.2, but the npk value is more like using 5-2-12, than what you were adding which was 5-2-6. So N or P may be low because of all the left over K. If the plants are small and the rez is big theres less of a need to change the rez out as often. Someone once told me to change the rez as often as the plant consumes the whole volume of the rez. I go a little longer in flower when the plant is drinking like crazy in five gallons with big plants. But in a 27 gallon tote with six sog plants, one rez change in two months seems like it may even be overkill.

Oh and if your plants are yellowing, im wondering if your using any calmag? Ro water or tap?

Sup Alien, thanks for taking the time to help bro. Since this is all new to me I still learning to read the plants as the meters only tell half the story. The yellowing looks like either a slight N def or the nutes are a little hot. Some leafs have yellowing in the middle and some are a little crispy on the edges. But most of it's on the lower part of the plants as the tops look pretty good except a what appears to be a little tip burn. It difficult to tell at this stage in my learning. Not every plant in the same tote has this issue either which is more confusing...two have no blemishes at all. They are all different strains by the way so I can see how one would like something the other might not. I think this weekend I might do a half tote water change which would be about 6/7 gallons but I'm not sure yet as it's not apparent it's needed but more of a question on my newbie behalf. They really starting packing on weight around week 5 and now some buds are about the size of a softball while others on the same plant are about the size of a golf ball. Most of the strains are 10 week strains with two being 13-14 week ones per the seed bank. Two of the biggest are blackjack and white castle...they are huge; so much in fact that I've had to tie them up. I guess what has surprised me is I expected to have to spend a bunch of money and feed the shit out of them and it's just not he case. Either the dynagro nutes are really strong, I had my expectations wrong on the amount of food or I'm doing something wrong. They even love my tap water and the PH is very stable ..no special RO or anything. All I seem to do is top off for a week or two then give them enough to get back to 1.2 which is not much at all. 3-5ml of foliage pro with about 10ml of bloom and 5ml of GH floralicious plus and it take 13 gallons of water at .8 EC to 1.2/1.4 then it takes two weeks to work it's way back down to 8EC.

I think this is what I'm seeing..looks about right. With the EC already at 1.4 I guess my only option would be to drain half the water and replace...thoughts?

http://www.growweedeasy.com/phosphorus-deficiency-cannabis

Pics? Sounds like mostly everythings pretty good.

The problem is you won't notice what your nutrient imbalances are until the most critical time in flower lol. It's really easy to keep plants happy and green all through veg and he first month or so of flower. But at somepoint they'll start devouring p and k at very different rates than n so you'll end up starving them in some elements and toxing them in others as you top of with regular nutrient mix.


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What everyone said.

The npk ratio gets thrown off after awhile.

Potassium gets eaten in the first 3-4 days.

In other words, rez changes are for ensuring correct nutrient ratios.

Also it helps prevent salt build up on the roots.

That said, I shoot for 14 days in veg and 7-10 days in flower.

Some might say it is waisteful to dump 2.0 ec but after awhile the ec will become "trash" salts that the plants can't use.

Also roots can produce a hormone that attracts root rot. Some you can't combat rot with rez changes.

kmog33 said:

The problem is you won't notice what your nutrient imbalances are until the most critical time in flower lol. It's really easy to keep plants happy and green all through veg and he first month or so of flower. But at somepoint they'll start devouring p and k at very different rates than n so you'll end up starving them in some elements and toxing them in others as you top of with regular nutrient mix.


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Yeah, if you always top off with water still in res who knows what nute ratio is in there. That water that was still in the res is an unknown because you don't know exactly what amounts of what nutes the plant took from it and left in it at what levels.

Especially in cases where you see any problems accuring you should restart with a fresh res.

I could't get all the way in the back where some of the lager flowers are and moving them makes my arm too sticky..lol but here are some picture from up front and I hope you can see the yellowing in this. I turned off the hps lights in hopes of a good pic. These are mid week 7, I hope I'm doing ok for a newbie..this is my second attempt at this.

Nitrogen looks good. Id say minor nutrient burn from the curling and burnt tips. Good work, just dial it back a bit on your third attemp. I hope you kept a log on ppms vs. weeks.

What's a good way of changing the nutes out, I can't really move this much weight with my chronic pain condition. I've looked at a electric transfer pump but they are around $100 . The room is right next to the bathroom so I'd love to just run a host from the tote to the tub and drain it. Also, last time I tried to put a lot of fresh water in the cold water seem to shock the shit out of them...what's the best way to do all this if I need to drain and refill? Thanks guys, I'm really trying here to succeed and be self reliant but it seems I'm messing up.

Alienwidow said:

Nitrogen looks good. Id say minor nutrient burn from the curling and burnt tips. Good work, just dial it back a bit on your third attemp. I hope you kept a log on ppms vs. weeks.

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No sir ..no log but live and learn and I will start logging as I can see how much it would help. Thanks bro!

hondagrower420 said:

What everyone said.

The npk ratio gets thrown off after awhile.

Potassium gets eaten in the first 3-4 days.

In other words, rez changes are for ensuring correct nutrient ratios.

Also it helps prevent salt build up on the roots.

That said, I shoot for 14 days in veg and 7-10 days in flower.

Some might say it is waisteful to dump 2.0 ec but after awhile the ec will become "trash" salts that the plants can't use.

Also roots can produce a hormone that attracts root rot. Some you can't combat rot with rez changes.

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I get really lazy in veg. But I use 3 gallon buckets for my dwc. I've found 3 gallons is the perfect amount so that when they're drinking it, as long as your levels are in check, I have to refil the buckets often enough that i never really swap out my res as they empty themselves. As seedling I will let them use the same water until they start to fade almost lol. Then I'll swap water. Flower my girls get fresh water every 3-5 days.


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taproot said:

What's a good way of changing the nutes out, I can't really move this much weight with my chronic pain condition. I've looked at a electric transfer pump but they are around $100 . The room is right next to the bathroom so I'd love to just run a host from the tote to the tub and drain it. Also, last time I tried to put a lot of fresh water in the cold water seem to shock the shit out of them...what's the best way to do all this if I need to drain and refill? Thanks guys, I'm really trying here to succeed and be self reliant but it seems I'm messing up.

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I always drain and refill the reservoir right after the last feeding of the night, so the water has all night to come up closer to room temperature. Also helps evaporate some of the chlorine out of the water; not that I worry much about chlorine, but it can't hurt.

taproot said:

What's a good way of changing the nutes out, I can't really move this much weight with my chronic pain condition. I've looked at a electric transfer pump but they are around $100 . The room is right next to the bathroom so I'd love to just run a host from the tote to the tub and drain it. Also, last time I tried to put a lot of fresh water in the cold water seem to shock the shit out of them...what's the best way to do all this if I need to drain and refill? Thanks guys, I'm really trying here to succeed and be self reliant but it seems I'm messing up.

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I only have a 5 gal bucket res, so I just use this little $8 pump -http://www.amazon.com/Uniclife-Submersible-Powerhead-Hydroponic-Certification/dp/B00ZW6OHHY/ref=sr_1_6?ie=UTF8&qid=1456512413&sr=8-6&keywords=water+pump
Mine is a 80GPH(gallon per hour) and they make a 400GPH for only $15 so you could just get that one.

But exactly as kmog said, once I'm in flower my plant drinks the whole res weekly so I just pump the small amount of water out of the bottom of the res and pump the new stuff in. When I'm in veg and my plant & roots are small enough for me to lift and set in another bucket i actually take the res bucket to the tub and empty it and spray it out with the shower head so that I don't have residue build up(if you wipe the sides of res with paper towels you'll see what i mean by build up) even though once i get to flower i can only pump, but i figure any bit helps. Root rots the mother fuckin devil so anything to not get it I say.

While on the topic one thing I can suggest is to at least make sure once the grow is done you give your res a really really good cleaning. If you have any hoses for water level make sure you clean those fuckers out, I did two grows and then on my third grow I got root rot and the only thing i can contribute it to is that there was gunky crap build up in that water level tube that I found when cleaning the shit outta my res. Keep in mind little parts of the roots brake off every now and then and you'll see them floatin around at the bottom, those will eventually sit in the tube and start forming gunky crap once they all collect into a bunch.

One thing I do to clean my pumps and feed hoses is fill the res with a strong bleach solution, put both the pump and the outlet of the feeding hose into the res, and plug it in. Just let it run for a half hour recirculating bleach solution through itself. Then multiple pump flushes with a several reservoirs full of clean water so that the pump is thoroughly rinsed out.

its not necessary, but its worth doing.

Yeah, I tend to be overly anal about some things - mostly to make up for at least some of the stuff that I completely overlook. Kind of balances out in the end.

But I figure, what the hell. I'm spending a couple of hours doing other stuff like general grow room cleaning, scoping for nanners or hermies, checking to make sure no buds are getting shaded and moving plants a little bit if I need to get them into better light, checking for signs of insects or bud rot, fussing over the clones, whatever. I've usually got several sets of plants running at any given time - mature plants in bloom, younger clones or seedlings in early veg, and fresh clones. I can easily spend a couple of hours any given day just poking around and peering at the plants. If it's a night that I'm doing a lot of that stuff, I figure, let's flush out the pump and hose. I do it every couple of months or so, unless - on a very rare occasion - a reservoir goes funky on me, in which case it's an automatic.

Skunk Baxter said:

Yeah, I tend to be overly anal about some things - mostly to make up for at least some of the stuff that I completely overlook. Kind of balances out in the end.

But I figure, what the hell. I'm spending a couple of hours doing other stuff like general grow room cleaning, scoping for nanners or hermies, checking to make sure no buds are getting shaded and moving plants a little bit if I need to get them into better light, checking for signs of insects or bud rot, fussing over the clones, whatever. I've usually got several sets of plants running at any given time - mature plants in bloom, younger clones or seedlings in early veg, and fresh clones. I can easily spend a couple of hours any given day just poking around and peering at the plants. If it's a night that I'm doing a lot of that stuff, I figure, let's flush out the pump and hose. I do it every couple of months or so, unless - on a very rare occasion - a reservoir goes funky on me, in which case it's an automatic.

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I change my res every 2 weeks. Works good on the every 2 week harvest. Just make for a lot of work. Luckily I have good homies and they help out to lessen the load. I am super anal about my grow too, so I always feel like I could keep it cleaner or spend more time on it one way or another.

Change as often as you can, that is the simplest answer. Water that is sitting will lose many things and there is no way for anyone to know for certain without expensive digital pens to measure each element daily could one know. Experiment until you find the right way to do it for your environment as each one is unique.

I run 100L res's and depending on what cycle I'm in Res refills are from 5-14 days. Early veg refills can be every 14 days but full on veg and flower could be 5-7 days. My PH is a good indicator for me as to when it's needed as well. If PH starts to drop on a daily basis then I know it's time if water levels are still ok. As twisted said every system is unique. I have noticed that with the chilled Res, things do stay more stable. Lots of great suggestions in this thread. I never add back or top up but I have read tha that's ok but once you add back the total of the Res the n it's time to refill.