Grow Mediums Why change water out?

[lykaboss]

So i got to thinking about this... Why do you really need to change your nutes out every 7 days? What happens to them after 7 days? In DWC they always say...... 7 days change em.... Ok will do... but why?

Do they go bad? do they break down? I don't understand why you could just add more water and up the strength....

Hopefully someone can shed some light on this

BTW i do change my buckets every 7 days.

 

[Waximus]

Hi lykaboss, When I do hydro, I usually can go 10-14 days between res/nute change. One important reason is that, over the time the nutes are in the res/bucket the plant may use more of one nutrient than others in the soup, so after a while the nute mixture is out of balance, and can cause nute lockouts if the concentration of remaining nutes gets too high. By changing it out regularly, you are resetting the balance of nutes while removing excess (unused) nutrient components. When I was doing 10-14 days between changes, I'd add back pH'd water or additional nute solution, as needed. I'd keep a close eye on my TDS/EC, and mix nutes to stay on track with the EC readings. I never had a problem with waiting 14 days, though once I went to 22 days and was getting the early signs of K lockout. Hope that helps!

 

[lykaboss]

Right on, much appreciate the input. That clears some of it up. I heard of people growing in under current systems, that only change there nutes out 3 times.... fill up for veg.... run threw all of veg same solution just increasing the strength, dump out and refill for bloom... run the bloom cycle until flush...

When i heard that it got me thinking about DWC

 

[pop22]

So i got to thinking about this... Why do you really need to change your nutes out every 7 days? What happens to them after 7 days? In DWC they always say...... 7 days change em.... Ok will do... but why?

Do they go bad? do they break down? I don't understand why you could just add more water and up the strength....

Hopefully someone can shed some light on this

BTW i do change my buckets every 7 days.

Lots of variables. It really depends on what nutes you use, the average res temp, if you use something like Aqua Shield, how fast you plants consumes the nutes. You CAN go without a res change, using the Kratky Method. Kratky's method is no res change, top up inly if needed. You prevent root rot by leaving and airspace of about an inch or so between the bottom of the netpot and the surface of the water. I have two kratky buckets going right now. So far, no root rot. One is even all organic. You don't use airstones either. I've not seen anyone grow cannabis that way yet so I decided to give it a try. One has been going over thirty days, the other is about 3 weeks.

I change my DWC res every 7-10 days. Some nutes breakdown over tine also. I res change also give you a chance to correct PH outside the res so there's less shock to the plants.

 

[DWCocha]

Waximus nailed it bro :Cool bud:

 

[Muddy]

Lyka, if you go with the Current Culture RDWC you won't have to change the system as often. Those systems are very nute efficient and generally only require about half the nutrient strength of DWC. I can usually go about 3 weeks between system dumps in mine.

 

[jackmc]

Hey Lyka, From what I understand you change the nutes to prevent "salts" from becoming too concentrated in the res as the plants suck up what the need and leave the rest behind. What type of "salts", I have no idea. Perhaps that is what Waximus is describing.

 

[DWCocha]

Perfect for a DWC scrog then ?"AFN smoke out"

 

[Anthropolis]

Hey Lyka, From what I understand you change the nutes to prevent "salts" from becoming too concentrated in the res as the plants suck up what the need and leave the rest behind. What type of "salts", I have no idea. Perhaps that is what Waximus is describing.

"Salts" is just chemistry speak for any of many chemical substances, Potassium for example. Not to be confused with "table salt" hehe which is NaCl.
http://en.wikipedia.org/wiki/Salt_(chemistry)

 

[Muddy]

The salts are a bi product of nutrient utilization. In soil, they are the white deposits you see on the inside of your pots. Yes, they are also the primary reason that hydro systems need to be changed regularly. Once the salts start to build up the pH and ppm become unstable.