when water evaporates and PPM's rise...

[Marshall]

In the past I have dumped my DH and AC water back into the rez and this kept my rezes pretty full during the cycle, loosing minimal water and keeping PPM's pretty stable. Now I dump the water because both units sat unused for a year and I am concerned with the rust etc that developed inside them so I just dump the water.

On a 100 gallon rez, I can loose up to 50 gallons over 10 days towards the end of flower, 4x8 table.

The PPM's go up. Is this truly because the plants are getting overfed or is this because the water is evaporating, leaving a more concentrated solution behind?

Plants look good, maybe a tad dark. but no nute burn, etc

Do I scale back the nutes or just top with fresh water every couple days?


BTW my PH rises to so that whole PH rise/PPM drop vice versa isnt playing out here


If I do scale back nutes, do I just scale back back everything evenly? base nutrients, additives etc

 

[FreezerBoy]

Water evaporating from an open tub leaves nutes behind and thus raises PPM.

Constantly pouring water into a res to maintain PPM suggests over feeding in a sealed res. Is yours open or closed?

 

[hippydan]

When the res is filled, you add your nutes, etc. Take a TDS reading. After a few days the water line will fall, due to evaporation and plants sucking it up. If you take another TDS reading now, it's almost useless. Make sure you fill the res back up with water to the normal level, THEN take your TDS reading. It'll let you know how much nutes your plants are actually using. This will let you adjust how much you are feeding them accordingly. Hope this helps a bit. Freezerboy answered your question but I thought I'd try to add a bit!

 

[FreezerBoy]

In a sealed res, there's no evaporation. All water loss comes from feeding. Feeding may cause EC to rise (overfed), fall (underfed) or remain flat (just right).

Sealed or open, always measure both EC and pH before add back. If you add back prior to measuring, you have no idea what to add.

Unless you're using a waterfall for aeration, using an open res seems like an unnecessary math nightmare.

 

[Marshall]

oh man, i had a brain fart. I should have put more thought into the fact that the plants were transpiring the majority of the water.

I run an open res, never thought about sealing it. E&F table, water just pours back in.

Wouldnt be hard to cover

So what to scale back? everything? just the nutrients? additives?

 

[hippydan]

So what to scale back? everything? just the nutrients? additives?

Depends on how much water has evaporated. Fill the res back up and take another TDS/EC reading. Go from there.

 

[CannabisFox]

Feeding may cause EC to rise (overfed), fall (underfed) or remain flat (just right).

Why is it possible for the ec to rise trouth plants using the nutrients?

Is it because they stop takin those nutes to prevent takin damage from too much nut?

 

[FreezerBoy]

Why is it possible for the ec to rise trouth plants using the nutrients?

Given food and water in abundance, plants take what they want and leave the rest behind. They're always thirsty but, their appetite varies. Put more food in the water than they want, they drink the water and leave the food. The remaining water is now super charged with food.

The more food in the water, the greater it's ability to conduct electricity. The more electricity conducted, the higher the EC. Because nutes are acidic, the higher the EC, the lower (more acidic) the pH.

 

[benzo]

Hey freezer boy, regarding these following posts

In a sealed res, there's no evaporation. All water loss comes from feeding. Feeding may cause EC to rise (overfed), fall (underfed) or remain flat (just right).

Given food and water in abundance, plants take what they want and leave the rest behind. They're always thirsty but, their appetite varies. Put more food in the water than they want, they drink the water and leave the food. The remaining water is now super charged with food.

The more food in the water, the greater it's ability to conduct electricity. The more electricity conducted, the higher the EC. Because nutes are acidic, the higher the EC, the lower (more acidic) the pH.

I have a sealed res, but am feeding with blumats.

The plants are being fed as the nutrient mix is being 'dripped' into the medium (coco). The plants, or roots, don't actually have direct access to the res. So in my case, what is the case of the EC/PPM fluctuation?

Sealed or open, always measure both EC and pH before add back. If you add back prior to measuring, you have no idea what to add.

Is this called "topping off"?

When I need to add to my res, I mix in 5 gallon increments so the nute ratio stays the same (or so i thought).

I do notice sediment at the bottom of the res if I don't clean it out monthly. But with a small pump which turns on 15 mins only 4 times a day, and an air stone running 24/7 the res stays pretty well mixed.

Am I doing this wrong or just over thinking?

 

[jumanji2]

Given food and water in abundance, plants take what they want and leave the rest behind. They're always thirsty but, their appetite varies. Put more food in the water than they want, they drink the water and leave the food. The remaining water is now super charged with food.

The more food in the water, the greater it's ability to conduct electricity. The more electricity conducted, the higher the EC. Because nutes are acidic, the higher the EC, the lower (more acidic) the pH.

I'm about to jump in with a bunch of vets but here I go lol..
Hey Benzo or FB was wondering if u can chime in on this..I'm handwatering coco(hempys) 1st week of flower
nutes are
GH micro/bloom H3ads 6/9. Feed once a day
900ppm,PH 6 going in,
1500ppm runoff, PH is close to 5.(using drop kit)
Temps are 86/ 45% humidity.

Plant is healthy as can be from the looks.
Right before I switched to flower I had the same issue, got it back down to normal readings by flushing with low ppm, worked my way back up, now 2 weeks later same thing.
I first thought it was due to low humidity I had in my veg room (30%) and the plant drinking more water rather than nutes but now I'm thimking I've been def overfeeding correct?? I have had no problems at all which didn't make me think about it. Should I back off on the nutes then?
If coco holds nutes until the plant needs it I don't want to keep flushing, give low ppm nutes and deprive it especially in an important time. Or is this a non issue?
Some say the run-off isn't important cause that's coming out anyways. Or am I just over thinkn this lol thanks for your time.

 

[FreezerBoy]

I have a sealed res, but am feeding with blumats.

The plants are being fed as the nutrient mix is being 'dripped' into the medium (coco). The plants, or roots, don't actually have direct access to the res. So in my case, what is the case of the EC/PPM fluctuation?

NOT a coco user! I had to Google blumats so take all this with a grain of salt... (better yet, post in the Coco Forum)

Are you recirculating? Drip to waste? Which way is pH going?

If recirculating, Coco used to be alive. I wont hazard a guess what happens to the water filtered through it but, I'd think it would have to be... something. Coco aside, the chances of you hitting the exact water:food ratio is pretty high. Return leftover water to the res that's of a different ratio, the tub ratio will change as well.

Drip to waste. Temperature can have some effect on readings. Aeration can raise pH. Aeration forces CO2 out, CO2 exists in water as carbonic acid. Remove acid, raise pH.

You mention sediment. I'm not saying, I'm asking: Does water with sediment measure the same as water with nutes in full suspension? JUST A GUESS, I'd think not. Our meters/pens/wands have two electrodes that pass electricity between them and sediment isn't between the electrodes, it's on the bottom of the tank. But, THAT'S A GUESS!

I've seen GH Flora Micro fall out of suspension (never Grow or Bloom) The official fix is to mix with an equal amount of hot water and use at 2X the rate. That helped but, I bought a new bottle anyway.

 

[FreezerBoy]

900ppm,PH 6 going in,
1500ppm runoff, PH is close to 5.(using drop kit)

D'OH! Shoulda read ahead. 900 in, 1500 out... Coco's doing something.

My best GUESS would be two separate regimens. Just as a fantasy example say: water every other day, feed every Saturday.

You and Benzo should head over to the Coco Coir Forum where they KNOW what they're talking about. My solid media grows were called "the backyard." Drop seed, wait six months, smoke plant. I never had to deal with your types of questions because the dirt did all the work.

 

[jumanji2]

Lol I got u bro. Thank u anyways tho

 

[benzo]

NOT a coco user! I had to Google blumats so take all this with a grain of salt... (better yet, post in the Coco Forum)

Are you recirculating? Drip to waste? Which way is pH going?

Drip to waste. Temperature can have some effect on readings. Aeration can raise pH. Aeration forces CO2 out, CO2 exists in water as carbonic acid. Remove acid, raise pH.

Sorry, shouldnt of mentioned blumats. Its basically drain to waste. Coco never gets inside the res and nothing gets recirculated..


The PH drifts UP. nothing drastic, but it happens and I was just curious why. & i believe ya answered it.

must be the air stone/water pump and res temp effecting the temp in the sealed res then.

maxijet 1000 water pump is set to turn on 4 times a day for only 15 minutes to keep it mixed. ill set the timer to only have it come on twice a day instead

I also have an air stone running 24/7
Would you suggest putting the air stone on a timer?


for taking the time to reply

 

[guest 77721]

Here's a helpful explanation that I came across a while back and saved...