I was discussing things in another thread here which started getting into a totally different discussion, so I thought I'd better start a thread specific to that topic.

I have a hybrid 4" PVC tube setup which is kinda like a DWC and NFT mixed together, nutrients continuously are pumped into one end of the PVC tubing and exit at the other end back to the reservoir, which is aerated well via air bubbles.

I can get into more specifics about my setup if you like, but I'm trying to stick to the nutrient situation at hand.

My plants are now 2 weeks old, and seem to be doing well, but I've noticed a bit of leaf curl happening and slight yellowing of the 1st leaves of the plant.

I'm using "Aqua Flakes" brand nutes, and reverse osmosis filtered water which is always really high pH.
There is some resin filter for the final filter which is supposed to make the water more alkaline for better health when drinking it.

When I mixed my 1st batch of Aqua Flakes, it called for only 2.5ml per gallon (man, why do they mix imperial with metric!!) and I have a large reservoir, but am only putting 55 liters (that's 14.5 gallons)of water in it at a time.

Link to Aqua Flakes page

When I measured the EC/PPM in the nutes, it was only 160 or so, and I was told on this forum to keep adding nutes until the EC/PPM was up to about 250-300PPM, which I did.

At that time, the pH was still high, so I used pH down to correct that down to about 5.8.

After a couple weeks, the nutes were getting really scummy and nasty, so I changed it today, and mixed up new nutes, and followed the mixing chart exactly for veg growth at 2 weeks as per Aqua Flakes instructions.

The instructions call for 6.5ml per gallon, which equals 94.9ml of nutrients (that's 94.9ml of part "A", and 94.9ml of part "B")

I mixed it up, and stirred well, and then took a ph reading, and it was already low this time, around 5.7 or so I think (I need a better pH monitor, just using a test kit right now, not a meter), so I didn't have to add any pH down.

I assume the nutes are self pH correcting or something?

I then took a PPM reading with my TDS meter, and was shocked to see it is 760!

The water straight out of the RO filter is only around 26PPM before I add any nutes to it.

Why is the PPM SO high, and are my plants gonna keel over now from an over dose of nutes, or should I trust the mixing instructions from Aqua Flakes?

How much should I be concerned about the PPM reading??

The nutes are circulating in the tubes as we speak, so I hope someone out there can set my mind at ease so I know I'm not gonna kill my plants!

Thanks!

Actually, I "may" have answered my own question regarding the PPM, which is a relief.

According to the webpage I "just" found, the Aqua Flakes PPM for veg in the 2 week period should be 840:

Feed Chart Link

Why does this differ so much from the earlier advice to keep my PPM around 250-300??

I think there is something I'm missing, but cannot seem to figure it out, your help would be much appreciated!

Seems too high to me. Their formulas are for commercial veg growing.

You could siphon out about half of that and top up with RO water or wait to see if they burn.

Save what you siphon out and add it back as the plants drop the ppm.

Store in a cool dark place so algae doesn't grow in it. If you have it add some peroxide to preserve it.

I would remove that extra filter when you make water for your plants but then you should have some CalMag to make up for the lack of minerals in the RO water.

So if this is the "wrong" mixture ratio, what would be the correct one for next time? What should the PPM be??

Thanks again for your reply!!

hey NScooknet, if you got that 250-300ppm figure from me, I was only saying that for reference with my clones, when you said you were at about 150ppm before.

840ppm for 2 week old plants is too high, in my opinion also.

In DWC I go from about 250-300 with clones to about 700-800 for veg, then up to about 1400 or so peak in flowering, about 5 weeks or so in. (depending) (.7EC conversion.)

Couple more things here. The point of RO water is getting everything out of it, so as LabRat advocated, I'd also get rid of that additional filter thing. But if you do add cal mag, 26ppm isn't going to be anywhere near enough, if you actually need it. In other words, I doubt that 26 ppm of who knows what in your water is really doing much either way.

Next, I don't know if I'm saying this the right way exactly, but good RO water, or distilled water, has nothing in it to create a pH. Real world, first thing here, don't try to measure RO water with a PH probe, you will literally ruin your probe. I guess you haven't gotten a probe yet, but you'll see that in the directions. Next, the higher your tds, the more ph up or ph down you have to add to change it. I have no experience with aqua flakes, but almost none of the normal nutrients end up at the right ph without being corrected. They usually end up too acidic, and have to be brought back up.

Unfortunately I can't tell you if 760ppm will burn your plants, there are way too many variables involved in that. But I'd probably back it off a little just to be safe..since 760 is a pretty big jump from where you had it before, right?

Thanks Harv,

I added more water to the nutes, and the PPM is now around 540.

Hopefully that is ok.

It's that "resin" filter on the output of the RO filter setup meant for drinking water that raises the pH, and to start with, our well water is very alkaline. The PPM of the well water here is around 500-600 of god knows what, so that's why I bought the RO filter for our drinking water.

It's not exactly easy to bypass that resin bead filter, I'd have to take it all apart and then reassemble it every time I need to change the nutes, a big pain, so I hope I can work around that.

I would feel more comfortable having a pH probe and knowing the "exact" pH, but now that I know about RO and the probe thing, I guess I'll have to stick to the test kit.

Unfortunately, it's not all that accurate, I'm guessing most of the time due to the color of the test.

Right now, it's at the bottom of the scale, so I was hoping the pH was where it should be, but I am now thinking it may be too acidic.

I hate screwing around with baking soda, because it's easy to overshoot then have to add pH down again, plus I'm told that adding baking soda can raise the salt level and mess up your plants.

I wonder why I had to add the pH down before? I guess because my nutes were so weak.

I also lowered the lights down to about 2 inches over the plants, they seem to have grown today noticeably!

By the way, should I be misting the plants with water on the leaves?

If so, do I use my crappy high PPM well water, the nutes, or distilled water to mist the leaves??

Thanks again for all your help, it's so funny that Health Canada allows you to grow it, but gives you NO help or any guidance whatsoever, it's like they WANT you to fail!

There's still a ton I don't know about all of this myself, for example, I don't know why I can have 2 different containers of the same tds and pH, and when I add the same amount of pH up, they can end up at different pH levels. But I do know how most of this stuff works in practical reality though. I'm guessing from your reply here that I wasn't able to completely get across what I was going for with the measurement thing. What I was getting at was with a tds in the single digits, or even in the low 20s, it's not just that it damages a pH probe to check it, it's that if you did check it, and actually got a reading, it would be totally meaningless anyway.

It would be meaningless because of the thing I mentioned earlier about the higher the tds, the more ph up or down you have to add to change the pH. If you have a tds in the single digits or 20s, it takes so little to change the pH, it just doesn't matter.

Occassionally people will comment on how they pH correct the RO water they flush with, like the 2 drops of ph down they added is going to matter one tiny bit. Lol.

It only matters once you get something mixed into the water, and get some kind of tds, that's when you check the pH.


A little more on your RO system. That add on thing for the drinking water is just a marketing gimmick. You can drink RO water, I drink 4ppm water all day. It won't leach the calcium from your bones, or anything weird you might read online. If it did, I'd probably already have broken multiple bones by now. I'd guess the tds leaving your RO membrane is probably 4-10ppm, if it's a good system, then it goes through that resin thing and gets another 10-15ppm of something alkaline on top of that? Or maybe it leaves the membrane at 26ppm, and that resin thing is doing literally nothing. Have you checked the tds before the resin thing? Either way, not a big deal, that's all I'm getting at here. I'd remove it, but you could just leave it there and forget about it, doesn't matter either way.

Baking soda, or sodium bicarbonate, isn't really an ideal pH up, due to what it is made of. Again, this isn't something I know a ton about, but in general I'd rather add something I know the plants like or are going to use, like something with potassium..

Thanks again for all the great info, I honestly don't know what I'd do without forums like this, it's not like my doctor can answer any of these questions, nor would the people who supply the seeds (Health Canada)...LOL.

It was just an added bonus that the RO filter system I bought was what was needed for hydo setups, it's funny, I bought the filter for making our water safe to drink here, and I built the hydro system to grow veggies in the winter, it was only after those things were already in place that I decided to grow my own medical cannabis to help treat my condition.

If I remember correctly, the TDS of the water leaving the membrane in the RO system was around 12PPM, and after the membrane is that weird resin bead filter, and a carbon finishing filter which bump the TDS up to around 26PPM as the finished filtered water ready to drink.

I am not concerned about all that PPM stuff and drinking water like you mentioned, I'm sure low PPM water is not gonna hurt anyone, afterall, I'm pretty sure that all the minerals, trace elements and micro nutrients one needs comes from their food, and not the water they drink.

Anything has got to be better than drinking that crappy Canadian springs water, and I wouldn't dare drink our well water, it's bad enough I shower and brush my teeth with it!

I understand the pH and TDS relationship thing much better now, thanks for explaining it further.

I'll pick up some pH down soon and not use that baking soda anymore, just to be safe, and I'll be adding some epsom salts as suggested here also.

I'm still a bit confused about exactly what PPM I should be aiming for when it comes to mixing my nutes up, especially when I actually shouldn't really be following the manufacturer's suggestions.

Am I kinda in the right range with it sitting at around 600 or so as it is right now?

I've been reading a thread here on another nutrient that I have available locally also, it's made by "Plant Prod" and it's simply called 10-6-16 hydroponic fertilizer.

Any thoughts on this?

It's only 5 bucks for a 250 gram container, but I'm not sure if it is good to use, or if it is appropriate from veg straight through to flowering stage.

The manufacturer has no info on this product on their page, but it is still sold, so I'm not sure if it is old stock, or something else.

Any thoughts on this?

The thread I am referring to is HERE

Also, what about misting the leaves of myplants, should I be doing that?

If so, with what?

The nutes, tap water, distilled water??


Thanks!

10-6-16, I don't know, I think it might not have enough phosphorus. Say if my botanicare pure blend pro hydro bloom is 2-3-5... 3/5=.6, whereas 6/16=.375. With the cal mag I add being 2-0-0, I figure my actual ratio is probably like 3-3-5. But I also have been adding botanicare's soil bloom, 1-4-5, so I could be sitting at 3-4-5, I really don't know. Either way, that's a lot more phosphorus than 10-6-16.

The tds/ppm thing, it can really vary. People can hardly believe how low of a tds I used to grow with in aero, and I can hardly believe it myself either. 360ppm in the middle of flowering, you could probably drink that all day. I don't know how much of that had to do with the strain, all I know is the plants looked good, grew quickly, and my nutrient costs were practically nonexistent. It sure was weird swapping out of my dwc veg units at a higher tds into the aero for flowering at a lower tds, but it worked.

I then built a dwc setup alongside my aero to do a comparison grow, and totally messed that up. I underfed so bad that I actually ended up delaying my harvest trying to give the plants time to heal, and doing that, I ended up with hermies. Live and learn.. I just couldn't believe how much higher of a tds I needed. Checked my tubs yesterday, 5 weeks into flowering, I'm hitting 1500+ppm. I'll dilute that back down a little today.

So I'm sure you can see how I wouldn't really know what your system/plants would want, since your setup is sort of a hybrid. I'd guess it'd run more like dwc than aero though. I don't really know what it is about aero that allows such a low tds, maybe the spray just blasts those nutrients into the roots, I don't know.

If I had to guess, I'd say yeah, 500-600 is probably about right for now, but the plants will tell you. Too low, the leaves will look yellow from not enough N, you'll get rust colored blotches from not enough calcium (cal mag), you'll get weird color fading and dead looking leaf surfaces from P and/or K. Tds too high, they get dark, then it's tip burn, edge burn, partial leaf surface burn, then whole leaf surface burn. I've burned entire plants to a crisp. That's actually how I learned my "strategic leaf removal" thing. I burned one plant so badly it dropped most of its leaves...but when it recovered, its buds grew huge, outyielding the adjacent plants by about 3:1, and they were more crystally too! Sure didn't expect that. Ever since then, I cut leaves to allow the light to get into the plant, and to hit as much bud surface as possible. I don't do it to the point that I waste light, I just create "light tunnels" if you will, down into the plants. I typically remove almost 80% of the leaves as the buds fill in, carrying them out of my room in a 5 gal bucket. The difference in yield and quality is like night and day. That is a real "grow secret" right there. You just have to know how/when to do it.

But I'm gettting a little off topic with that. As far as your question about spraying leaves, or foliar feeding, my thoughts on that are, well, in nature, rain is basically distilled water, and it washes any crap, like dust and dirt off the leaves. In my garden, I never spray my leaves, because it's a sealed room, it's clean, and I don't foliar feed. I never understood the idea of foliar feeding in the first place. Plants get nutrients from their roots, not their leaves. So why would you want to apply nutrients to the leaves? But I know people do, and even on my container of botanicare's "liquid karma" crap, it has directions for for foliar feeding. I have never done it though, and never will. The only thing I ever spray is azamax, for spider mite control. It's based on the same shit that neem oil is, but unlike neem oil, it actually works! If I start seeing spider mites, I spray my clones, veg plants, plants in early flower, my floor, my dwc lids, everything with that shit. It leaves a sticky coating on the lids that the spider mites hate to walk across, for a long time.

If you do want to mist your leaves though, in case you don't know, don't do that immediately before or during the time your lights are on. At least not with real bright lights, because those drops of water act like little magnifying lenses, and they'll burn your leaves with the light.

Don't worry about getting off topic, I need all the help and hints I can get, thanks for sharing those very helpful bits of info!

I added 1tbsp of epson salts to the nutes, and that brought it up to about 629PPM now, I hope that's gonna be ok.

I also plan on adding it to my tomatoes in the crap sandy soil in my garden as well...lol.

I should clarify that my setup is not using the "aero" feature at this point, I for some reason couldn't get the sprayers to work right, so the flow of nutes is strictly supplied via one jet at the end of each tube.

I am really worried that I'm gonna have root cloggin issues in that 4" PVC pipe, the roots of each plant are already around 6" long, man they grow fast!

So what's with the hydrogen peroxide?

What is it for, what does it do, and when/how should I use it?? I'm guessing it has something to do with oxygen exchange?

I have neem oil, I was hoping it would keep the slugs and ants off my sunflowers outside, but it doesn't seem to be doing squat.

So should I spray the leaves when it is dark then?

I guess I don't really need to spray them at all from what your saying?
Thanks again!