A Matter Of PPM

[Captain Kronic]

I have been thinking/reading about a question I have burning a hole in my head... no wait... that was that last bong rip... oh well, here is the question in question!

I have been learning this indo, soil less, hydro recipe. I can't seem to find a definitive enough answer in any of my texts!
If your recipe starts out w/a PPM of about 1400 when it is a fresh batch, should you or should you not try to keep the nutrients at about the same PPM level throughout it's usage?
Or... does that depend on the recipe being used?
It just seems to me that if the recipe is at prime PPM numbers when freshly mixed and applied, that you would want to keep it there as long as you could during that particular batch! Wouldn't you... thoughts?

 

[Xlr8]

I have been thinking/reading about a question I have burning a hole in my head... no wait... that was that last bong rip... oh well, here is the question in question!

I have been learning this indo, soil less, hydro recipe. I can't seem to find a definitive enough answer in any of my texts!
If your recipe starts out w/a PPM of about 1400 when it is a fresh batch, should you or should you not try to keep the nutrients at about the same PPM level throughout it's usage?
Or... does that depend on the recipe being used?
It just seems to me that if the recipe is at prime PPM numbers when freshly mixed and applied, that you would want to keep it there as long as you could during that particular batch! Wouldn't you... thoughts?

Do you mean topping off nutes between res changes? I prefer to change my solution once a week and not top off in between (maybe add water if they are aggressively drinking, but only in rare occasion when needed). I think the roots take up what they need when they need. They cherry pick mineral elements they need most and I don't know for sure what they are utilizing other than the total PPM. If they aren't needing much nitrogen for example why should I top off and give them more each time. So.. I don't top off - just religious about changing nutes weekly. I'm sure a lot of people do, though, and grow successful beautiful plants. Many ways to get end result!

 

[Captain Kronic]

Yeah, I don't mean to top it off w/more nutes... I am talking about topping the reservoir off w/H20 to bring the nute count back up to it original PPM numbers!
I seem to be loosing a lot of H20 out of the solution by way of plant uptake and evaporation, in other words... after about 4 days on a new batch I notice the PPM went from 1410 to about 1650.... so, I added about 10 Gals of H20 to bring the PPM back to about 1450.
Seems to me that you would want to keep that optimal "fresh batch" PPM numbers the whole way through each batch, or... as close as possible w/o causing problems... make sense?

Thanks for your feedback xlr8!

Do you mean topping off nutes between res changes? I prefer to change my solution once a week and not top off in between (maybe add water if they are aggressively drinking, but only in rare occasion when needed). I think the roots take up what they need when they need. They cherry pick mineral elements they need most and I don't know for sure what they are utilizing other than the total PPM. If they aren't needing much nitrogen for example why should I top off and give them more each time. So.. I don't top off - just religious about changing nutes weekly. I'm sure a lot of people do, though, and grow successful beautiful plants. Many ways to get end result!

 

[PrairiePoet]

I was confused on your first post as well. But you have cleared that up very well.

You are right, as the plants uptakes water, the PPM will increase. Though I'm not sure that adding just enough water to bring the PPM back to normal is what to worry about.

I like my water level to stay as high as possible. I add water back in every other day (or more during the last weeks of flowering). I try to adjust the pH to get it back inline of where it needs to be.

My two thoughts on doing it this way are:

When roots are exposed to air, they either die off, or create a hard shell on the outside. This is done to keep the roots from drying out. Once this outer shell is created, then it won't shoot off as many child roots from this area. New roots only come out when the mother root is under water. Same as in dirt, exposed root die.

If you let the water level rise and fall three to four inches, then you loose that much where new roots can grow out.

Keeping the water level up, decreases the amount of loss of root area. Allowing more roots to grow out is always a good thing.

In hydro, I equate the water as dirt. I just now don't have to water, and I get faster growth. The nutrient mix is like water and nutes for soil. Just like you don't water ever day, you don't fertilize hydro every day.

So.. the quick answer for me, is No. I don't worry about the PPM on watering. I just worry about the pH and water temp.

Prairie

 

[medme]

i used to worry about all that stuff,,,,,,,, now i just grow it,,, remember its a weed... i use that 3 part stuff from general hydroponics and just keep adding mixed water to my buckets. my plants do just fine... the key is i watch the tips of my leaves(the sun leaves), i want "JUST THE TIPS" burned,,, that means i'm max on my nutes,, and they grow SUPER..

 

[Xlr8]

I was confused on your first post as well. But you have cleared that up very well.

You are right, as the plants uptakes water, the PPM will increase. Though I'm not sure that adding just enough water to bring the PPM back to normal is what to worry about.

I like my water level to stay as high as possible. I add water back in every other day (or more during the last weeks of flowering). I try to adjust the pH to get it back inline of where it needs to be.

My two thoughts on doing it this way are:

When roots are exposed to air, they either die off, or create a hard shell on the outside. This is done to keep the roots from drying out. Once this outer shell is created, then it won't shoot off as many child roots from this area. New roots only come out when the mother root is under water. Same as in dirt, exposed root die.

If you let the water level rise and fall three to four inches, then you loose that much where new roots can grow out.

Keeping the water level up, decreases the amount of loss of root area. Allowing more roots to grow out is always a good thing.

In hydro, I equate the water as dirt. I just now don't have to water, and I get faster growth. The nutrient mix is like water and nutes for soil. Just like you don't water ever day, you don't fertilize hydro every day.

So.. the quick answer for me, is No. I don't worry about the PPM on watering. I just worry about the pH and water temp.

Prairie

Great response Prairie - nicely said.

Based on my set-up, I don't seem to get any "dry roots" per say as a result of decreased water in the reservoir, but I can see this happening in certain hydro set-ups.

That said, I think I would add H20 for the purpose you mentioned only if it were needed (root protection). Otherwise, I would just worry about PH and temp as you said (and as I do as well).

Also worth noting possibly - The nutrients I use advise not to top off your reservoir with more nutrients OR more water. They advise doing neither because if you utilize their calculator, it will work fine with fluctuations like this.

I personally don't think nutrients should be maxed out for most people - it's not needed, expensive, and you also don't have to sweat any of these sort of issues by being maxed out.

Just my 2 cents worth!

 

[Captain Kronic]

Good feedback... thanks all!
Not overly worried about the roots getting dry as I use the grodan blocks. My PH is always about 5.8 to 6.8, never too far either way. My temp is always a steady 63f, so that's no worry.
No, I was just wondering about the the added benefits (if any) to keeping the PPM at the optimal level. Apparently it makes no diff... viola!

 

[Captain Kronic]

So, I didn't really feel like the meat of my question was clear enough for me. I went looking and found what I was looking for... then I had the brilliant idea of looking on the Gen. Hydro site and found just what I was looking for in a way I could understand... momma always did have a way of explainin things so I could understand... LOL
Anyways, I think this answers the original question very well, and I quote:

WHEN THE RESERVOIR LEVEL BEGINS TO DROP, SHOULD I TOP IT OFF WITH FRESH WATER OR NUTRIENT SOLUTION?

Answer: If you drain, clean and remix the nutrients every 7 to 10 days, it's okay to top off with fresh water daily. As plants consume nutrients and water, the nutrient strength in the hydroponic reservoir will change. GENERALLY, nutrient strength should run between 800 to 1500 parts per million (ppm). Your exact ppm requirements will depend on your circumstances and style of growing.

Anyways, thanks again for the feedback peeps... none of us knows more than all of us!

 

[cryodude]

Very interesting Captain K. where did that info come from. Seems like a big variation in nutes, i'm thinking that changes that much because if different stages of growth/flowering??

 

[Captain Kronic]

Like I said cryodude... I got it right off the General Hydro web site, I am using their 3 part Flora nutes.

It makes perfect sense to me to keep the numbers PH/PPM/Temp as close as you can to the day one original mix. Seems to me that these are the optimal numbers for the particular stage of growth the plant is in... this seems so clear and makes so much sense to me... I think maybe I don't talk to gooder cause I think the principle of the big question has been pretty much misunderstood.

Maybe I smoke too much or too early... LOL

 

[cryodude]

Ah okies. Well i have a such a learning cover to overcome still. and i haven't even gotten into the garden part yet.. can't wait, oh but i have to! It's never to early unless you have a reason not to or shouldn't!

 

[Captain Kronic]

I've come to believe that this situation of mine is just something that I have to deal w/on a day to day basis... could be worse!

I have been supplementing daily, adding to my nutes about 6 to 8 Gals of H20 a day in a 32 to 50 Gal reservoir to get the PPM down below 2000, the max readable by my multi.

That is to say that if I take the PPM reading down to about 1500... it will be over 2000 the next morning regardless... the ladies (sour D mostly) don't seem the mind the elevated numbers.

Even w/a weekly rez cleaning and a nute change twice weekly, I still will have to augment the nutes the very next morning.

Bitches are taking a hell of a lot of H20, especially now in the later stages of flowering.

Not sure how much actual nutes are being absorbed, I suppose enough though, they are pretty healthy and look to finish strong.

My point is that... I guess this is par for the course for my setup.

Just wanted to update the info here for future need to knows!

 

[PrairiePoet]

Morning Capt'

I didn't go back and read through your posts to get some info, so I'll go from my not so good memory.

Haven't you also been fighting humidity? If not, then I really am confused. <g>

The plants are taking up a large amount of H2O from the res. Then transpiring that into the grow room air. Sounds like the plants are sweating a bunch.

I don't remember the temp range of your room, but would it be possible to try and lower it? My thought is that having a higher room temp the plants transpire more, which causes them to drink more.

I don't know, just a thought the beautiful morning, as tehe sun comes peaking in and I'm getting baked while reading here at 420.
[Virtual Pass the Pipe]

Prairie

 

[Captain Kronic]

(takes the virtual hit... aaaahhhh)

With the experimenting I did w/fans, intake and exhaust, I believe I figured that RH prob out for the most part. My temps have only been near or just over 80 for the last couple of days. Normally they are just a bit lower!

The plants daily use of H20 has always been somewhat high.

Guys I know, including the one that got me to try indoor never have the issue even w/all things equal except location and room size. In fact, most don't even check PH or PPM, I'm talking not once in 9+ years.

You have a point there Prarie and I have given that much thought, I feel that you are right! I have looked and don't see this problem w/anyone else though, even those w/low RH values... that's why I have not stopped looking.

One thing I have thought is that since my rez temps usually hang around 61 to 66 or so, that the plants are taking up the H20 and not the nutes; from what I read, that temp is a bit low for max nute availability... then again, I'm a noob and don't have much personal experience to draw on here.
I do know of a few guys that run shit colder than that and they pull off great stuff for harvests. They keep saying, don't sweat the lil shit, if it works... leave it alone!

I can't do that... it's not good enough for me just to see that it works for me. I want to know why it does or doesn't and how I can make it better!

So currently, w/temps at about 75/80, RH at about 45/50 in the light cycle and 65-72 w/RH about 45/60 in the dark, if I mix a 32 Gal batch of nutes, the PPM start point is about 1550 or so... by the next morning, I have to add 6 or more Gals of fresh H20 to bring it back down to say 1600 or so... I change nutes twice a week because of all the H20 I add, I figure best to try and keep fresher nutes available.

This is run on a 4x20 table w/40 plants ranging from 1.5 ft to 2.5 in height, run o the mill girth.

It really only bothers me because I can't find others who have the same rate of H20 usage that I do and it makes me think shit could be way better... AAAARRRRGH!

And Prarie, thanks for chiming in... I appreciate the ear time.. +rep

 

[Bill C]

So currently, w/temps at about 75/80, RH at about 45/50 in the light cycle and 65-72 w/RH about 45/60 in the dark, if I mix a 32 Gal batch of nutes, the PPM start point is about 1550 or so... by the next morning, I have to add 6 or more Gals of fresh H20 to bring it back down to say 1600 or so... I change nutes twice a week because of all the H20 I add, I figure best to try and keep fresher nutes available.

It really only bothers me because I can't find others who have the same rate of H20 usage that I do and it makes me think shit could be way better... AAAARRRRGH!

I'm currently running a 25 gallon reservoir with 16 plants in hydroton. They just started week 4 of bloom. Our temps are about the same, but my RH has been a little higher. I add about 3 gallons of water daily to replenish what they use. I add enough water to get back to 25 gallons, regardless of my PPM reading. After I add the water, I check pH & TDS. My pH is fairly stable during grow, but my PPM drops every day. I change my reservoir every 7 days.

I always figured the TDS is kind of like a fuel gauge in my car. Just because it says 3/4 doesn't mean I have to fill it up with more fuel. A plant will use what it needs from the solution even as the PPM drops. Just like your car will continue to use what it needs as the fuel level drops.

I have seen a lot of recipes that call for adding half strength nutes every other time you top of your reservoir. I tried that for a while, but it was more of a pain for me and I couldn't tell any difference than just topping off every day with plain water.

From my point of view, keeping the pH in the proper range will pay off much more than keeping the TDS in a range. My girls are always thirsty, especially during the blooming phase.

 

[Xlr8]

(takes the virtual hit... aaaahhhh)

With the experimenting I did w/fans, intake and exhaust, I believe I figured that RH prob out for the most part. My temps have only been near or just over 80 for the last couple of days. Normally they are just a bit lower!

The plants daily use of H20 has always been somewhat high.

Guys I know, including the one that got me to try indoor never have the issue even w/all things equal except location and room size. In fact, most don't even check PH or PPM, I'm talking not once in 9+ years.

You have a point there Prarie and I have given that much thought, I feel that you are right! I have looked and don't see this problem w/anyone else though, even those w/low RH values... that's why I have not stopped looking.

One thing I have thought is that since my rez temps usually hang around 61 to 66 or so, that the plants are taking up the H20 and not the nutes; from what I read, that temp is a bit low for max nute availability... then again, I'm a noob and don't have much personal experience to draw on here.
I do know of a few guys that run shit colder than that and they pull off great stuff for harvests. They keep saying, don't sweat the lil shit, if it works... leave it alone!

I can't do that... it's not good enough for me just to see that it works for me. I want to know why it does or doesn't and how I can make it better!

So currently, w/temps at about 75/80, RH at about 45/50 in the light cycle and 65-72 w/RH about 45/60 in the dark, if I mix a 32 Gal batch of nutes, the PPM start point is about 1550 or so... by the next morning, I have to add 6 or more Gals of fresh H20 to bring it back down to say 1600 or so... I change nutes twice a week because of all the H20 I add, I figure best to try and keep fresher nutes available.

This is run on a 4x20 table w/40 plants ranging from 1.5 ft to 2.5 in height, run o the mill girth.

It really only bothers me because I can't find others who have the same rate of H20 usage that I do and it makes me think shit could be way better... AAAARRRRGH!

And Prarie, thanks for chiming in... I appreciate the ear time.. +rep

What you say your environment is currently is just about absolutely ideal. I'd be very happy with your environment. PPM's are a little different depending on the meter, but I agree with Bill C, that you probably don't have to worry so much about TDS, top off with plain water, and just keep your PH in line - you should be fine. If not, try lowering your starting PPMs first so that it can climb without issue. In bloom, they suck up the water a lot!

 

[Captain Kronic]

I agree w/what you are saying... I wish the PPM would drop w/the PH but it rises drastically while the PH falls from about 6.1 to 5.4 or so by the next morning... if I leave the PPM at 1500 in the morning... by the end of the first 4 minute feeding, it will have risen a couple hundred digits.

I never add more nutes to the mix... seems useless when they aren't using the bulk of what's already available...

The biggest concern is me being a n00b indo guy and not having a lot of good info on this particular practice... I do understand more now than when I first started looking into this thanks in part to members like yourselves

I'm currently running a 25 gallon reservoir with 16 plants in hydroton. They just started week 4 of bloom. Our temps are about the same, but my RH has been a little higher. I add about 3 gallons of water daily to replenish what they use. I add enough water to get back to 25 gallons, regardless of my PPM reading. After I add the water, I check pH & TDS. My pH is fairly stable during grow, but my PPM drops every day. I change my reservoir every 7 days.

I always figured the TDS is kind of like a fuel gauge in my car. Just because it says 3/4 doesn't mean I have to fill it up with more fuel. A plant will use what it needs from the solution even as the PPM drops. Just like your car will continue to use what it needs as the fuel level drops.

I have seen a lot of recipes that call for adding half strength nutes every other time you top of your reservoir. I tried that for a while, but it was more of a pain for me and I couldn't tell any difference than just topping off every day with plain water.

From my point of view, keeping the pH in the proper range will pay off much more than keeping the TDS in a range. My girls are always thirsty, especially during the blooming phase.

I have to work it everyday to keep that atmosphere... it took me a whole grow (the first one failed) to figure out this room... I am still looking at changes that need to be made... need cash first though... LOL

This grow is almost done, the lessons learned will outweigh the harvest in terms of value... thanks for the input X...

What you say your environment is currently is just about absolutely ideal. I'd be very happy with your environment. PPM's are a little different depending on the meter, but I agree with Bill C, that you probably don't have to worry so much about TDS, top off with plain water, and just keep your PH in line - you should be fine. If not, try lowering your starting PPMs first so that it can climb without issue. In bloom, they suck up the water a lot!

 

[420pharms]

I think you should lower your tds about 100ppm at a time until you get to were your readings don't change more than about -50ppm in 24 to 48 hrs if res is sized right you could top off in 3 to 4 days with water only reducing the ppm too around 3/4 but no more than half of there original value ph and feed until half the volume or 3 to 4 days, then drain and refill with fresh and start again , foliage feed while on weak nutes to sup. this helps reduce nutrient build up in plants and ensures roots don't shock from too low ppm and I believe this makes roots look for nutrition stimulating root growth a hydro drought cycle sort of.

 

[Spicy2na]

I say all these PPM references are way over-rated. As long as you have a reference and can tell if there eating or drinking is probably the most important part.

 

[FrankFoster]

I just did the ppm on some backwoods hydro setup for my buddy the other day. Tuned him in right. See his regular water out of the tap is 130 ppm at 7.3 ph.

So we got him an acid azalea nutes for grow at npk 32 11 11, with fe and mg and ca. the powder stuff he can mix at 1 tsp per gallon.

At 1 tsp per gal the nutes go mixed at about/approx 400ppm + 150ppm + 150ppm plus the micro say 25 and the base tap water ppm 130. So the ppm off the bat is 855 ppm. But here is the kick.... 1 tsp per gal puts his water ph at 6.4 clean out of the tap.

So he can set ph and proper ppm every drain and ditch. But when he replaces the res he uses a gardening hose and flushes the hydroton every time with and extra gallon or so of h2o before pouring in the new reservoir mix.

The ppm would continually go up each res batch if the flushing wasn't done after draining. So he thought the ppm was resulting from his plants chewing up the water and leaving tds to elevate, but it was the system retaining salts between batches in the clay medium.

Good luck.