Changing water levels change everything?

[maryjanesjungle]

Ok so something I've noticed that's bugging me is that as the water level in my res goes down the PPM's go up and conversely the pH goes down. It's not a big deal to fix, I just add more distilled water which corrects both issues but is this normal? It's like the plants are sucking up just the H20 and not the PPM's.

 

[FreezerBoy]

What you're seeing is normal. Your solution is too strong. Because of this, your plant drinks more water than nutes so EC climbs. EC and pH move in opposite directions. Were your solution too weak, the plant would drink more nutes than water and EC would drop while pH climbs.

I prefer a small pH swing as there is no number at which all nutes are equally available. I slightly overfeed with slightly alkaline water. Over a two week period, EC climbs and pH drops and the addition of 4 gallons of tap water brings me back to my original numbers.

 

[icough2getoff]

I agree with freezerboy

How to tell if your PPM/EC is too high or too low

 

[maryjanesjungle]

Interesting, didnt know plants could do that.. well how do plants get nute burn if there able to drink just H2O then?

 

[maryjanesjungle]

I agree with freezerboy

How to tell if your PPM/EC is too high or too low

So I read that chart in your sig and I totally think the last example is what's happening to my plants. Due to overly warm growing conditions I'm sure. I've done all I can but at best I can only get temps down to around 84F. Also my 400W HPS is as the chart hypostasized very intense as it's less then a foot from the tops of the plants. Again nothing I can do about it at this point though. I find it funny the charts uses 400ppm in the optimal example and 700ppm in the over fed example. I assume these aren't recommended ppm levels just examples?

Below are some pics of my buds, been under 12/12 from seed but still grew bigger then I expected and thus why there so close to the light. Lights in a cabinet BTW so that's why I cant raise it. 400W was over kill as well imo, 250 next time. Problem I felt I was having as I near harvest was tric production. Oh well, there starting to get more trics on them so maybe all is not lost but hopefully next time I can do a better job on my environment. Thanks for that chart.

 

[FreezerBoy]

I find it funny the charts uses 400ppm in the optimal example and 700ppm in the over fed example. I assume these aren't recommended ppm levels just examples?

The problem here is two fold. One, every plant is different. Two, PPM doesn't mean anything. It especially does NOT mean parts per million. PPM meters do not measure ppm, they measure EC. Unfortunately, they don't display EC, preferring to reduce the EC reading to nonsense through one of at least 5 conversion factors (X500, X640, X650, X700 or X768)

As a complete guess, I'll say 400 ppm suggests the X500 scale which would be an EC of 0.8. I had my grow locked down at 0.8 for a month. Nothing moved but the water level. But, growth slowed and turned yellow. Most likely nute lockout from pH rigidity. There is no pH number at which all nutes are fully available. Now I feed at 1.0 so my EC will climb and my pH drops. EC 1.4 (700 ppm on the X500 scale) is WAY too strong for me. Your mileage could vary considerably.

 

[maryjanesjungle]

The problem here is two fold. One, every plant is different. Two, PPM doesn't mean anything. It especially does NOT mean parts per million. PPM meters do not measure ppm, they measure EC. Unfortunately, they don't display EC, preferring to reduce the EC reading to nonsense through one of at least 5 conversion factors (X500, X640, X650, X700 or X768)

As a complete guess, I'll say 400 ppm suggests the X500 scale which would be an EC of 0.8. I had my grow locked down at 0.8 for a month. Nothing moved but the water level. But, growth slowed and turned yellow. Most likely nute lockout from pH rigidity. There is no pH number at which all nutes are fully available. Now I feed at 1.0 so my EC will climb and my pH drops. EC 1.4 (700 ppm on the X500 scale) is WAY too strong for me. Your mileage could vary considerably.

hmmm,.. i don't understand the math you speak of. If parts per million aren't knowable then what should I keep my ppm reading at, whatever "it" is. Would you agree that my plants are locked out too seeing as there sucking up mostly water? If so is there a way to unlock them, and if not will they mature just at a slower rate? As for plants being different one is of the strain Flo and the other 2 are bag seed.

 

[icough2getoff]

Freezerboy is right, plants can vary quite a bit as to how strong they like their nutes. Most strains I've grown don't need more than an EC of 1.4 and often their peak flower is less. In general though, what the ppm says doesn't really matter. What matters is how it's rising or lowering. The general rule is if it's going up from day to day you dilute, if it's going down then you add more nutes. In your situation, I would start with a fresh batch of nutes with a lower ppm till you see it eating more healthy.

If they are being over fertilized, the plants wont just take longer to finish but the final product will be of less quantity and quality from what it could have been.

Here's a chart that might help you understand the math Freezerboy was trying to explain

 

[ItsGrowTime]

hmmm,.. i don't understand the math you speak of. If parts per million aren't knowable then what should I keep my ppm reading at, whatever "it" is. Would you agree that my plants are locked out too seeing as there sucking up mostly water? If so is there a way to unlock them, and if not will they mature just at a slower rate? As for plants being different one is of the strain Flo and the other 2 are bag seed.

You're asking a multi-part question so Ill break it down.

The way to get around all that ppm stuff is to pay attention only to your ph readings and adjust accordingly. As Freezerboy stated, ppm is pretty much meaningless by itself. Your ph will tell you whether you are overfeeding or underfeeding. I dont want to rewrite all of it so check out my post toward the bottom of page 1 of this thread: http://www.icmag.com/ic/showthread.php?t=95027

Plants can take up a lot of water without locking anything out. For example, I have a 22gal reservoir and I have to top off 2 to 3 gal of plain water per day. I only top off nutrients every 3 days. My plants are taking up a lot of water and just the nutrients they need and it's no problem, sitting at 5.75ph and 1070ppm in the sweet spot. The key is that my top offs with nutrients are based on what the ph says. Also as stated, that sweet spot will vary from strain to strain. You'll understand when you read the link above.

If you have a nute lockout, you need to flush with plain water and Clearex or similar flushing solution to resolve the lockout. I doubt you have a lockout but telling us your current ph and ppm would help. It just sounds like your nute solution is too strong but not deadly strong. You can fix that by removing some your nute solution and replacing it with plain water. It takes time to get the hang of dialing in your nutes.

 

[FreezerBoy]

hmmm,.. i don't understand the math you speak of. If parts per million aren't knowable then what should I keep my ppm reading at

Apologies for what I now see as only half an answer. The trouble with ppm and tds is in conversations like these. Define 100º. The American says warm, the Canadian says boiling, the scientist says below freezing. All are right. As is the geometry teacher when he says they're all wrong. PPM means nothing in conversation without a reconversion number on which all agree. 500 PPM could be an EC of 1.0, 0.78, 0.77, 0.71, or 0.65. EC means EC no matter who's talking.

As long as you can calibrate your meter, you can run a garden with ppm. The plant can't read, write or do arithmetic. It doesn't care what the numbers are. If your meter tells which way numbers move and how fast, that's really all you need. The exact number you want is that which causes the least and most dependable drift (under the theory that a small pH swing is better than none)

Remember that manufacturers nutrient charts aren't meant to fit your plants needs. They exist to force you into buying more nutes than you need. Many have luck with Lucas' 0-8-16 formula. 0-3-6 is too strong for me. Your ppm meter will allow you to talk with your plants. It just won't let you talk to us without the conversion factor.

 

[maryjanesjungle]

hmmm,.. from what you guys are saying I'm gathering only EC and pH matter, not PPM, which is frustrating seeing as I only ever looked at ppm's and pH. How exactly do I figure out my EC though? I have a Hanna HI 98129 Combo tester so I'm sure it's doable with it I've just always looked at pH and ppm's like i said. My readings were 5.8pH, 1000 ppm's and there is a third reading I've never known what it is. Its symbol looks like a "pS" but with an opening at the top of the "p" like a "u" and its reading was 1900. Is that EC or something I use to figure out EC? I'm getting more burning so I just took a gallon of water out of my res and added straight distilled water so now I'm at 6.1pH, 650ppm's and 1200 p/u S. I really would like to be able to "talk to my plants" so I appreciate the help guys

 

[FreezerBoy]

While I may have a giant mad on for PPM, your plants are illiterate. They don't know and they don't care. As long as you can map the rise and fall of your numbers, you and your plants are conversing fluently. Don't go dropping $150 on a BlueLab Truncheon for my sake.

Anyway, to answer your actual question ... The backwards "u" or topless "p" is microsiemens or microsiemens per centimeter (us/cm). ms/cm is millisiemens per centimeter. 1ms/cm=1000us/cm. The conversion factor is X=ppm/(us/cm). If X=1000/1900, then X=.526. If X=650/1200, then X=.542. It would seem that your meter is trying to use the .500 scale (hanna usually does but, not always). It's possible the difference in numbers is due to differing temperatures at reading time.

Whatever your nute chart says, cut it in half,see which way your meters move and go from there. The idea is to get them to move as slowly as possible. My pH swing is from 6.0-5.6 over a two week period.

 

[ItsGrowTime]

hmmm,.. from what you guys are saying I'm gathering only EC and pH matter, not PPM, which is frustrating seeing as I only ever looked at ppm's and pH. How exactly do I figure out my EC though? I have a Hanna HI 98129 Combo tester so I'm sure it's doable with it I've just always looked at pH and ppm's like i said. My readings were 5.8pH, 1000 ppm's and there is a third reading I've never known what it is. Its symbol looks like a "pS" but with an opening at the top of the "p" like a "u" and its reading was 1900. Is that EC or something I use to figure out EC? I'm getting more burning so I just took a gallon of water out of my res and added straight distilled water so now I'm at 6.1pH, 650ppm's and 1200 p/u S. I really would like to be able to "talk to my plants" so I appreciate the help guys

I too use the 98129 so lucky for you lol. It's a .5 conversion meter by default (tho it is adjustable to different factors) so a ppm reading of 1000 is a 2.0EC. A 500ppm reading is 1.0EC. That's how conversion factors on ppm meters work. Ignore the third reading, just another way to read EC/ppm.

Based on your results from removing nute solution and adding back plain water, your ph tells you (since it rose a lot!) that you are now underfeeding at 650ppm. You should add back some nutrients. I think your original 5.8 and 1000 was a pretty good place for your res if the ph rose that much. 5.8 is considered widely as the ideal hydro ph. If it rises much then its time to add back nutrients. If it falls, then straight water only. Remember that ph and EC/ppm are inversely related. If ph falls, you are overfeeding. If it rises you are underfeeding. Use that principle to swing the ph between 5.5 and 6.0 with it spending most of the time at 5.7-5.9. Did you read my post in the thread I linked? Are you using ph up or ph down to change the ph at all?

Looking at your pics I dont think you have nute burn or lockout. I think your lights are too close and it's light bleaching. It's hard to avoid if you keep lights close.

ETA: if your res is sufficiently large enough for your setup then adding back a lot of water doesnt matter much on a day to day basis. Its when your res is too small that it causes a problem.

 

[Horst Bulau]

I had my grow locked down at 0.8 for a month. Nothing moved but the water level. But, growth slowed and turned yellow.

I had the same happen recently when I moved my plants to my bloom room and NFT.

I was kinda lost because my EC was the same 0.9 as it was in my seedling bubbler before transplant. Healthy seedlings turned yellow from the bottom and eventually stopped growing altogether in that NFT.

I later discovered that there was a change in my nute setup which I hadn´t taken in account: I had started using silica as precaution and it made a change. That silica needs more Ph-down to get to the same 5.8... which means that my Ph- adjusted silica-water actually has an EC of 0.8 without any nutes in there yet , I just checked it again. That would be 400 ppm in a Hanna meter.

How do you take that "basic-EC" into account? I seem to underfeed while my meter shows high EC:s and there really isn´t much nutes at all, say, 1/8 of Lucas shows straight 1.8 EC at Ph 5.8 ... that being 900 ppm in Hanna scale. "Half-strength-Lucas" reads EC 2.4... 1200 ppm in Hanna again.

Like now, I have Herer and Passion #1 in a bubbler at seedling stage, a couple of weeks old. After a few leaf pairs, the lower leaves are turning yellow again. EC is not moving at all, new growth is fast and pretty - but the yellowing is faster so I will not win this. White pretty roots showing. My total EC is 1.2 now with Lucas nutes, at Ph 5.8 which is steady... am I running at EC 0.4 in effect or does the total reading count?


The weirdest thing is, I think I understand some of the EC / Ph thing by now, I have many other plants doing fine in different hydros. Just the hemp doesn´t do well at all. Different strains going on, I´m just about to give up on growing hemp altogether.

I hope this post fits in this thread.

 

[FreezerBoy]

Sounds like you have some pretty hard water. You may want to add nutes to unadjusted tap water and let it sit for a while before measuring pH and adjusting. I don't know what silica is supposed to do in a grow but, it sounds like it's fucking you up.

The EC reading is what it is. Though in your case, a greater degree of the reading is probably coming from calcium, magnesium, flouride and whatever else your tap puts out as opposed to NPK. Consider GH hardwater Micro which leaves cal-mag-sulpher etc out of the bottle. RO water is another possibility.

Not ragging on anyone but, in my informal survey of meters, pH meters are a complete crapshoot if they work at all. Of all the types out there, the Hanna was the most universally despised and mistrusted. It could easily be off by 0.5 or more meaning your pH could be anywhere from 6.3 to 5.3.

You could be suffering lock out from bad pH as I believe I was. You could be using such hard water that keeping EC low means the plants are starving for food. What does your water pH/ EC read straight from the tap?

 

[Horst Bulau]

Sounds like you have some pretty hard water. You may want to add nutes to unadjusted tap water and let it sit for a while before measuring pH and adjusting... cut... You could be using such hard water that keeping EC low means the plants are starving for food. What does your water pH/ EC read straight from the tap?

Thank you very much for replying Freezerboy, this is bugging me big time and I still find it hard to give up. I am a pot connoiseur, sort of, and my weed supply is ok with no growing... but I like to grow things and I also like to solve mysteries, obviously.

And my apologies to MJJ in case this is going OT. I´ll do my best keeping this on topic.

Now:

I´m flushing my 3"-4" plants with plain water now in a CuttingBoard. My tapwater has a 8.2 Ph and 0.09 EC. After adjusting Ph to 6.0 which I did now , my EC rises to 0.38 . No nutes.

I´ll forget silica for now because I obviously don´t know how to use it. When I add it and back Ph down to 6.0 my EC will be around 0.85. The lower I adjust my water Ph, the higher the "empty" EC gets even without silica. Silica keeps Ph dead steady and prevents most root problems, that´s why I got some in the first place.

My successful Skunk #1 seedlings were grown without silica , I was watching the plants and adding more GH Lucas strength ( from 0.5 EC to some 0.9) and I thought I was getting the hang on grass hydro growing. Wrong, not yet.

My Micro/Bloom ratio was 1/1 at the start and went towards 1/2 later on. This is how they looked like :

My main problem has been the "discovery" of EC meters. I thought I can just mix one part Micro / two part Bloom in a cup with some water, then add it to the res while simply reading the EC meter. It worked with sheer luck once with those Skunks, I saw clearly when there was too much nutes so I just diluted a little and followed the EC meter.

I obviously didn´t have any clue about the actual nute amount then either but it worked. Ahh, there was some Diamond Nectar, too, I now recall.

Now I´m getting back to the basics because those readings are different , depending on the Ph and water additives the EC reading can vary like hell - meanwhile there being the exact same amounts of actual nutes.

Too much too soon. My next move with these seedlings will be 1/10 of Lucas using milliliter measuring, not EC. I´ll let them flush for a few hours now first before I change the whole cocktail again.

Thank you very much !

 

[G33k Speak]

What you're seeing is normal. Your solution is too strong. Because of this, your plant drinks more water than nutes so EC climbs. EC and pH move in opposite directions. Were your solution too weak, the plant would drink more nutes than water and EC would drop while pH climbs.

I prefer a small pH swing as there is no number at which all nutes are equally available. I slightly overfeed with slightly alkaline water. Over a two week period, EC climbs and pH drops and the addition of 4 gallons of tap water brings me back to my original numbers.

wow!! lotta great info packed in that little post!

 

[sarek]

Thats interesting about ph though my expierience is that my ph always drifts down after about 10 days. Starts at 5.8 and day 14 would be around .5.5. But i always thought it had to do with bacterial acidic by-products. For example as time goes by bacteria and fungus eat root waste product which produce organic acid waste. Adding H202 usually raises ph to 6.3 from 5.5 which i assumed was a result of killing off bacteria. One good peroxide treatment will stabilize ph for a couple months.

But I had never considered ph to be related to ppm or fertilizer usage but I will try to see what correlation I can see.

 

[FreezerBoy]

Thats interesting about ph though my expierience is that my ph always drifts down after about 10 days.

While your EC does ... what?

Truth in advertising, I'm no scientist. I have simply parroted info that, in my case, turned out to be true. But, I'm using no organics or bennies or enzymes. Tap water, GH Micro, Bloom and the occasional pH down is all I'm running.

This is NOT a suggestion to change your nutes. Just wanted you to know where I was coming from.