Nutrient adjustment for budding, have used canna A/B, when to PK13/14?

[1love1earth]

So I've been growing in canna coco coir.

I let my plants veg for almost 3 months, a big mistake, I know, I was planning on taking a bunch of clones for outdoors, and it never really happened on that scale.

So I cut them back a tad and started flowering them.

They've been in 12/12 for just over 30 days.

I've got 3 2.5 gallon pots, 1 2 gallon, one 5 gallon, and 1 6 gallon, all under two 400 watt CMH aircooled reflectors.

I've got 1 hashberry, one satori, a few safari mix, 2 big bang, and 1 mandala #1.

I've been using canna A/B as primary NPK. I also use hygrozyme, cal/mag+, and have floralicious+.

I've also got PK13/14.

I've been using 1.3-1.8 EC, PH'd at 5.7-5.8

Recently I tied the plants waaay back so that what was vertical is now horizontal, which allowed me to drop my lights a ton, and give me the headroom I need to get through to harvest.

Due to a number of factors, I figure my normal flowering time will be increased by 1-2 weeks.

However my question is this:

When should I start using PK13/14, and how much should I use?

I've been told to use it this way in a post from another member:

"Throw in the PK at 0.5-1.5ml/l (2-6 ml per gal, or .5-1.2 tsp per gal) for 3-7 days anywhere between week 4-6 on an 8 weeker -that means you shall use it when your plants are fully stretched with all budsites in development and just about to start fattening up. PK is mixed first, then you add the A + B untill the peak EC is reached. (you replace some of the base-nutrients with PK)
-When you're done with that week of PK-boosting it is about time to lower the ec to about 2/3-3/4 of your peak level (or about ec 1,0-1,2). This level should then be kept for about 1 week and then lower it a bit more for the remaining days (ec 0,6-0,9). Stick to that until you finally have 7-3days left; and then switch to pure tap-water."

Now of course I have no idea how much 1 tsp per gallon yields in EC, and how much A/B I'll have to add to get up to peak EC.

Regardless, I'd love some feedback on when to use PK13/14, how much to use, etc.

Basically I've been on the same nutrient plan since the very start, just tweaking it up or down depending on how the plants look.

However now the "home stretch" represents an entirely different nutrient plan, and I need to know how much to give.

IE, should I keep the same EC I've been using? 1.3-1.8 or so?

How much PK13/14 should I be using?

Feel free to tell me in any way, whether it is tsp per gal, or PPMs or EC.

How much A/B should I be using afterwards?

When should I change the EC?

How should I PK "boost"?

Any and all information is greatly appreciated.

 

[1love1earth]

surely someone has some input on the nutrient adjustment needing for my final 30-40 days?

I greatly need info on when to start PK boosting, at what levels, for how long, and basically all nutrient related information from where I am now to harvest.

I know I'm coming up on the first real nutrient change/adjustment, and I have no clue how to proceed.

I'd certainly like input on the quoted suggestion above, as that's currently the only information I have to go off of.

 

[straight reggie]

*coughsearchcough*

so easy a cave man could do it

http://www.icmag.com/ic/showthread.php?t=61691&highlight=pk

http://www.icmag.com/ic/showthread.php?t=49777&highlight=pk

 

[1love1earth]

The problem I've been having is that even in both of those two threads, there really isn't much conclusive information.

Some use it from week 2 til finish, some use it for just one week, some for 3-4, and of course all at different rates.

Thus I'm a tad confused as to the best way to proceed.

I'm at about day "40", though like I said, after bending my plants down, I've still got alot of newer bud growth showing up, and TONS of budsites, I'll take pics today and post them.

I'm seeing some nitrogen overload on a plant or two, deep deep dark green.

Today I decided to switch things up a bit.

Took my normal mix that was at 1.6 or so (canna A/B and cal/mag making up the EC), and watered it down with tap to 1.25 or so, and then filled the rest with cal/mag and PK13/14 til I hit 1.6 again (also added more hygrozyme).

Of course I'm completely open to suggestions, and really really would like some conclusive info on PK, when to use it, for how long, and how much.

 

[straight reggie]

dude there isnt going to be conclusive answers. especially with PK. trust me ive read and searched before. everyone does there own thing. you gonna have people that follow the label and those that dont. just the way it is hommie. just gonna have to experiment.

 

[1love1earth]

alright, it's just my first real time around, and I was looking for a basic guideline.

Up until now, I had a basic idea of when to add more nutes, because I could recognize nitrogen deficiency, and add more.

Now with PK, I'm not sure what look for in adding more, or what too much will look like. I've been over the infirmary thread a whole bunch, but even so, there's not a ton of pics in there.

We'll see then I guess, I'll post some pics and give the folks here a chance to see, evaluate how I'm doing so far, and what I should be tweaking.

 

[straight reggie]

yeah no doubt man we can all understand that. really with whatever you decide to do with PK is dont over do it. in my last grow i used beastie blooms (pk boost) during the 3 week and 6 week. i had very good results. this time around im using it during week 2 and gonna use it until flush. remember this using PK boosters is not a necessity.as long as your plants are getting their basic nutes you will have a good harvest. also keep end mind that this is a learning experience every grow. and unless you just suck @ this game, you will get better and better. learn the basics of what your plants need then you can get fancy. keep if the good work my dude

 

[1love1earth]

Well here are some pics, I guess I'll make an infirmary thread as well, since on some of the leaves look like there's evidence of "malperformance" on my part.

Starting here:

spotting and that stuff at the edge blades of the leaf:



edge blades and tips:





Bud pics:




My younger (and un-topped) mandala #1 growing what appears to be an actual cola:




more bud:




And canopy:








Any suggestions/ideas for where I'm at for 30-40 days or so would be appreciated, (mind that I'm likely a little bit behind in flowering since I tied the plants back to give more headroom, I'll have a bit of extra flowering time added)

 

[1love1earth]

Pic of one half of the room:




and the other half:







Look at the two leaves above the first leaf, what's going on with them?





More evidence of something:




This one shows what I'm pretty sure is thrip damage on the 2nd to last blade.
we've broken out the spinosad and hit them twice now with it, should be OK.

Not sure what the spotting is about however.




bud pic:




curious damage



edges/blades look browned:




again, I've tied them back about 2 weeks ago, before that they were all pushed up against the lights, getting burned, fighting hardcore for light, there were about 4 more plants in there than now as well.

Thus they may be recovering still, but let me know how it looks.

Again, there are a TON of budsites on each plant, and that mandala#1 pic is the closest thing to a cola.

Some plants have over 30 budsites at least.

I'm wondering at what point I should "manicure" the lower growth that isn't getting much light, or should I just leave everything alone?

 

[1love1earth]

also, I'll look around a bit, but when do plants put on most of their budweight? Is it in the last 30-40 days or so?

Finally, any info on my plants is grealy appreciated.

 

[Greyskull]

Dude 1love1earth ease up some on your nute doses cause to me that yellowing going on at the tips is a sign of over fertilization. Cut back some on your nutes IMO. Check my grow - I get pretty good results Canna rules. I like to keep things pretty simple.... ebb & flow with 40g reserviors. Heres how I use Canna:


not trying to be the boss at all, but....
DON'T MOLEST THOSE PLANTS NOW ITS TOO LATE YOU WILL ONLY SCREW UP YOUR YEILD. You don't have massive colas because of all the budsights on each plant. Check it out... each plant is capable of producing a total of X amount of bud. When X is spread out over multiple sites you get what you got - a hellava trim job ahead of you. Sorry. The last week of veg I suggest you start your pruning program... you gotta look at you plants and prune accordingly. A pinch here and a snip there. DON'T OVER DO IT IN A SINGLE PRUNING SESSION. Personally, I prune weekly starting the last week of veg thru middle of week 2 bloom. I start by clearing the bottom feeder growth and lower fan leaves and then work the plants as they need to be worked. You have to know how the plants grow to optimize your pruning technique aka it will take a run or two for each plant

Have you checked out this site - the best nutrient for cannabis site in the world... courtesy Canna? www.canna.nl/english/index1.html
Canna's nutrient calculator (when it works on the website) is a very helpful tool. I pretty much use Canna's recommendations at 50% strength
http://www.canna-uk.com/wrapper/1

Good luck with the rest of your grow. Keep growing!

 

[1love1earth]

no worries my friend, the advice is well appreciated, and there are a number of rules I decided to break on my first grow.

#1, there are numerous strains that I am flowering. Big bang, safari mix (which is really several strains in one), hashberry, satori, and even mandala #1.

Big mistake, makes it hard to learn much about your plants on the 1st grow, just too overwhelming.

#2. Extended veg period with waaaaay too many plants in the room, caused them to stretch real high, get all pushed up against the lights, and got burned left and right when condensation formed on the reflectors.

#3. No LST'ing early on. Late transplanting. My current clones have been in keg cups for about a month, and that is still overkill. However they ARE being kept in good shape through LST, not nearly as bushy and big as others, but that's due to lighting I think, 105 watt CFL 5000k for them 24/0 (easier to run 24/0 without a 2nd light tight room to run a dark cycle).

#4. I tied the plants waaaay back, but sadly right after the stretch. I bought myself about 2-3 feet of extra headroom, but the plants seem to be mostly done stretching. While the occasional cola does reach for the light, most others don't.



I figured the reason to leave the less mature buds/smaller ones was exactly that, my yield will only be hurt by getting rid of them.

Certainly I have pruned off the bud shoots that were under the canopy, and getting crap for light, and looked sickly because of it.

Anything I could bring to the top of the canopy and tie there I've been doing.

There are still solid looking buds and nugs, in fact some of them are quite obscured by other bud/leaves, or not directly under the lamp, and look quite nice, which is curious.

Like I've said, I don't think I'll have a real good feel for what I got until I pull everything out for harvest, I keep finding nugs here and there, as the area is still a tad crowded.

I can tell my mandala #1, which was started much later (probably 6-8 weeks of veg)only 1.5 ft tall, and not beautifully bushy by any means (had to compete for light during veg), has much better bud development. It is much more consolidated, and appears to have the largest/most distinct cola, with several other "smaller" colas.

I've backed off on the nutes. I noticed the burnt tips much more after taking the pics, and many of the plants appear extremely deep dark green, a sign of too much nitrogen.

I wasn't certain if it was just too much nitrogen, or too high of an EC in general, so I backed off from 1.7-1.8 down to 1.3-1.6, more like 1.3-1.5 the last few waterings.

I've been PK boosting pretty heavily, about .5-.7 EC is PK 13/14, .3 EC is cal/mag+, and the rest is canna A/B.

I'm wondering how much PK13/14 I should use (ie EC/PPM) and for how long. My general plan, which could be completely wrong, is to start high on the PK13/14, and work my way down slowly.

Should the ratio of PK13/14 to canna A/B (and cal/mag I guess) remain the same until I start flushing, merely dropping EC/PPMs as time goes on?

Or should I boost real heavy for a week or two, then drop the percentage/ratio of PK13/14? Or when I cutback on boosting, am I going to keep the same ratio, and just drop the entire EC on a whole?

The other thing I've noticed is some form of leaf mutation. It seems to have started after the PK boosting, but I have no idea if it is due to that.

The new leaves emerging from the colas appear to be "flat", the blades are very indistinct, it doesn't really even quite look like a normal pot leaf.

Some of the buds on one of my plants are starting to look odd, and I think it's due to the tiny leaves growing in the bud being mishapen.

Regardless, I'll take some pics today for all of you.

What I'll be looking for are any and all nutrient suggestions, any information on the odd leaf formation and what it might mean, and finally any and all pruning suggestions.

Also feel free to suggest lighting height.

Should I tie upper colas back, and drop the lights as low as I can, or should I continue to raise them, and encourage the bud to reach upwards?

 

[Greyskull]

Aloha 1love1earth! DamnI know that took forever to type out.... kudos for the work you're putting in!

hard to learn much about your plants on the 1st grow, just too overwhelming"

I KNOW!! My first grow was in a homebox with Master Kush... thought I was cool vegging them for 30 days til they were 3ft tall then I tried to flower them. OOPS. The first one is the worst one, but think of all the good *experience* you already have now - you are on your way!

I figured the reason to leave the less mature buds/smaller ones was exactly that, my yield will only be hurt by getting rid of them.

Certainly I have pruned off the bud shoots that were under the canopy, and getting crap for light, and looked sickly because of it.

Anything I could bring to the top of the canopy and tie there I've been doing.

Exactly - that's the way!

There are still solid looking buds and nugs, in fact some of them are quite obscured by other bud/leaves, or not directly under the lamp, and look quite nice, which is curious.

Like I've said, I don't think I'll have a real good feel for what I got until I pull everything out for harvest, I keep finding nugs here and there, as the area is still a tad crowded.

Its gonna be lie X-mas & Hanukkah when your chopping.

I'm wondering how much PK13/14 I should use (ie EC/PPM) and for how long. My general plan, which could be completely wrong, is to start high on the PK13/14, and work my way down slowly.

Canna suggests adding the PK13/14 to the solution once 3 weeks before harvest @ 150ml per 100L (roughly 6ml per 40G). After trying a few different things, for me, I like to add it at 1ml per G when I see good bud developement (week 3); then 3ml per G at week 6. Only those 2 times - kicks ass for me. Seriously.

Don't worry about how green your plants are as chop day comes along - the are just super healthy. Wth Canna Coco, I have noticed the plants stay green even thru flush. Nothing to worry about. Healthy plants

 

[1love1earth]

see, this is one that threw me off, in the few threads I saw about PK boosting, folks were doing everything under the sun, and there was no real consensus.

Some use it for the duration of the grow once they start boosting, others like you only use it once or twice. (or is that two full weeks you use it for?)

I'm at a loss as to what I'm doing with my nutrients.

Right now I've got a mix of .5 EC PK, .2 EC cal/mag+, and I was going to top the rest off with A/B.

I mean, the quantities of PK13/14 you're talking about using are next to nothing, unless it was a typo, 150ml per 100l isn't 6ml per 40 gal. Unless you meant 6 tsp per 40 gallons, aka 30ml?

I used about 30 ml in my mix just now (6 tsp) , but I don't know how big the container is, it's at least 10-15 gallons in there right now I'd like to say, likely 30+ when full.

1ml per gallon equates to about 1 tsp per 5 gallons, which is much less than I have used.

Am I overdoing it?

I figured that a solid boost would be alot of PK, like .5 EC or so.

The old suggestion I had said to use .5-1.5 ml per liter, or about 2ml-6ml per gallon, approx 1/2 to 1 tsp per gallon, which is more along the lines of what I have boosted at.

That said, I should boost for one week, then return to pure A/B, then boost one last time?

What sort of direction is the EC going during this time?

Like during boosting, am I maintaining the normal EC/PPMs, merely replacing a bit with PK?

After the boost do I continue with the normal EC, or drop it off a tad and not replace the PK with more A/B?

I'm confused here, and clearly my plants had been getting too many nutrients, certainly at least too much nitrogen.

So right now my mix is as follows:

.5 EC of PK13/14, .2 EC of cal/mag, .6 EC of A/B, with a tiny bit of floralicious, rhizotonic, and silica mixed in.

Yielded 1.4 EC, and added more water to raise PH a tad, final result was PH 5.7 and EC 1.32/PPMs 900

 

[1love1earth]

also, besides the nutrient questions above, which are quite critical I feel, what about the lighting distance? Should I have them as low as I possibly can, or should I slowly bring them up, to encourage stuff to stretch up?

Also pics to come tomorrow that illustrate the different budsites, and the strange mutation/malformed leaves.

 

[bounty29]

You can see where I add in the PK boost. This is Rezdog's feeding schedule, so there must be something to it. (The KoolBloom is GH's equivalent to PK 13/14)

 

[Greyskull]

the quantities of PK13/14 you're talking about using are next to nothing, unless it was a typo, 150ml per 100l isn't 6ml per 40 gal. Unless you meant 6 tsp per 40 gallons, aka 30ml?

I tried to convert ml/G to ml/L... oops! Here's the real deal, as per the nutrient schedule I use & posted for you to review.

week 3 1ml PK13/14 per G 40ml total 40g rez
week 6 3ml PK13/14 per G 120ml total 40g rez

I use nutrients at about 50% the manufacturer's recommended dose

I'm at a loss as to what I'm doing with my nutrients....I'm confused here, and clearly my plants had been getting too many nutrients

It can be overwhelming, and its very easy to overthink and overanalyze. You have awesome nutirents. No need to worry about the lucas formula with Canna. I know the worst vice is advice, so I'm not going to give you advice. I will simply tell you how I got Canna Coco to kick ass for me
... and I use them at about 50% the manufacturer's recommended dose!

A) Start by having a goal EC/PPM range for each week.

THIS IS WHAT CANNA RECOMMENDS FOR EC/PPM PER WEEK IN FLOWER:
wk1 EC 1.2-1.7, PPM 840-1190
wk2 EC 1.2-1.7, PPM 840-1190
wk3 EC 1.3-1.8, PPM 910-1260
wk4 EC 1.3-1.8, PPM 910-1260
wk5 EC 1.3-1.8, PPM 910-1260
wk6 EC 1.3-1.8, PPM 910-1260
wk7 EC 1.0-1.5, PPM 700-1050
wk8 EC 0.0, PPM 000

*notice how the EC/PPM climbs, then falls towards the end

B) Then I fill up the reserviors. When full take the base water's EC/PPM (mine is EC 0.5/PPM 350) before you start adding nutes & additives.

C) Add the additives (Boost, Cal/Mag, Cannazym, PK13/14, Rhizotonic, Sweet, etc) one at a time @ 50% manufacturere's recommended dosage we can always add more later.

D) Add B first, then add A (I read in a Maximum Yeild adding B's first helps stabilize the solution's PH when added before A....) at 50% recommended dosage remember we can always add more later.

E) Check the solution's EC/PPM. If its within the goal range, then off we go. If it's LOWER than the goal range, then add more B & A carefully & in equal amounts until within goal range. If OVER the goal range, add plain water to dilute/lower.

F) Check and adjust PH to betwen 5.7 & 6.1

G) Top off the reservior with plain water as needed thruought the week. DO NOT ADD ANYMORE NUTRIENTS. Make those bitches eat all the food you give them - they will.

** Do not worry about how green your leaves are - they will stay green until you chop - even with a flush. ITS OKAY - nothing wrong with harvesting healthy plants, is there? Plants stay green with Canna Coco. As long as you flush for at least 3 days in coco you will have nothing to worry about except your dry & cure skills and abilities.**

Regarding the distance of your light over your plants:
Do you want loose fluffy buds or nice tight dense nugs? The closer & more intense the light the plants receive the better they'll put out. Test how close you can go by sticking your hand over the canopy for a few minutes - if its too hot & uncomfortable for your hand then its too hot & uncomfortable for your girls. Adjust the light height accordingly. I use aircooled reflectors, and am able to keep my lights 8"-12" above the plant canopy. My girls love me.

Here's some pics of what I do using Canna (hope its okay to post pics in your thread). I consistently yeild 550-600g per 4x4 with only 12 plants in 1.75g pots under 1Khps.




THERE IS NO CURE FOR CRAPPY GENETICS. IF YOU START WITH CRAPPY GENETICS THEN ALL YOU ARE DOING IS POLISHING TURDS.

I hope this helps you out... Canna makes the best nutrients.

 

[1love1earth]

wow, those are nice nugs.

Part of the other "genetic" problem, is that with starting with so many different strains, there was no actual selection based on budding quality, whereas if I was to pick one strain, and keep clones of the best budding plant, I could have done some form of natural selection to obtain my "supercut", which I think is what most folks do.

I am handwatering my coco, which also I don't like. Takes too much time, and is a real PITA.

If anyone has a simple suggestion on how to automate the system, whether it takes buying a few hundred worth of gear, I've got experience with pumps and tubing before (not for growing), and it really might be far easier.

I would really like to "automate" my watering next run. I don't mind actually doing it, like having to flip a switch, and sit there wet vac'ing water out of runoff trays, that's OK with me, but it'd be super sweet if it was recirculating, like what you are talking about, right?

Another question:

You say you merely top your resevoir off with plain tap? Are you also correcting the PH?

For me, I handwater, but oftentimes my resevoir/tub that I make my mix in doesn't get used all the way, and I've noticed that what was PH'd to 5.7-5.8 one day will turn into 6.4 the next day or two.

Now when you say 50%, are you talking the tsp per gallon? Cause surely you're not talking 50% of their EC/PPMs, which would be .6-.9 most weeks.

I'm guessing you more run off the low end, IE,

wk1 EC *1.2*-1.7, PPM *840*-1190
wk2 EC *1.2*-1.7, PPM *840*-1190
wk3 EC *1.3*-1.8, PPM *910*-1260
ETC, right?

I've by far outdone your PK dosing, and while I will return to your dosages tomorrow, my current mix was more like 2.5ml per gallon.

So I think I can do this, it's making more sense now.

One thing I need to decide is how many plants I want to run next run.

Currently I only have 6 clones, probably not the optimal number for my next flowering run.

I'm thinking maybe more like 12 of them, in small one gallons or something, well trained, just a bunch of single big colas.

Also I've started a new experiment of sorts, not sure if it'll do much good, but surely can't do any harm.

Wanted to mix it up with Co2, so I found a recipe for creating it with 2 liter bottles, yeast, sugar, and water. I just try to keep the mouth of the bottle under the buds, and in theory Co2 keeps coming out of the mouth, until the yeast is inactive, in which case you just rinse/repeat. Now I'm not turning my fans off or anything, but this is more of a passive Co2 system than active with a tank. Still, I figure for the $$$ (ie nothing really) investment, surely it can't do any harm.


Finally, one thing comes to mind that could be an issue. I use a milwaukee PH/PPM meter. Over time, I've had to crank the calibration dial for EC/PPM alot. Now if I run it against a solution, IE 1500PPM/2.2 EC (or something), I can always get it to check out, and even after a month of not calibrating it, the worst reading was only 1640 PPM, instead of 1500.

My concern is that when I first got my meter, the tap water would read .04 EC, whereas now, it reads .09-.12, and the PH reads higher as well (used to read 7.5, now 8.5), though again PH checks out on a calibration to 7.0 (perhaps I should get some 4.0 solution, and see how it checks out against that).

So to sum it up, the meter itself can always be calibrated, and those calibration readings can be repeated over and over, but how it reads the tap water has changed slowly over time, making me worry as to the accuracy of it's calibration.

However I cannot think of a way to cross check the calibration. Except maybe using a solution with a different value, IE calibrate on a 7.0 PH solution and then cross check against a 4.0 PH solution, and maybe the same thing for EC/PPMs, except I don't know if there are solutions other than 1500PPM.

Regardless, it does worry me a tad that somehow my entire measurements are off.

The nutrient dosages still 'feel' correct, but again, I've had to crank that calibration dial real real far over time to get it calibrated.

 

[Greyskull]

You say you merely top your resevoir off with plain tap? Are you also correcting the PH?

yessir. Always check & adjust PH whether topping off or not.

For me, I handwater, but oftentimes my resevoir/tub that I make my mix in doesn't get used all the way, and I've noticed that what was PH'd to 5.7-5.8 one day will turn into 6.4 the next day or two.

Just check & adjust the PH before you feed and you'll be chillin'.

Now when you say 50%, are you talking the tsp per gallon?

Exactly! If the label says add

SuperNute @ 20ml/Gallon

I interpret that to mean add SuperNute @ 10ml/Gallon.

I'm guessing you more run off the low end, IE,

wk1 EC *1.2*-1.7, PPM *840*-1190
wk2 EC *1.2*-1.7, PPM *840*-1190
wk3 EC *1.3*-1.8, PPM *910*-1260
ETC, right?

Suprisingly enough I typically end up close to the middle of Canna's recommended EC/PPM levels using 50% doses. The exception week is 3 weeks before done (wk6 in an 8wk grow, 7wk in a 9wk grow) when I give both Boost & PK13/14 heavily (for me) - that week I am usually over 100-200 PPM. Thats the week I love watching the PPMs fall thruought as the girls are eating up all their food - and them get swollen!

Here's my 8/8.5wk & 9wk schedules side by side. Not really much difference (though there is a mistake fpr 8/8.5wk's Sweet dose for week 8 - should be 25ml/g).

So I think I can do this, it's making more sense now.

That's the way to be thinking!


Regarding your meter I think the probe may be bad. I have a Milwaukee PH pen and I kept having to calibrate it every week... I finally brought it into a shop and they checked it for me - thats when I learned the probe was bad. Maybe you can take it into a local shop for the to have them heck it out. I definately recommend picking up a cheap PH Drop test kit to keep on hand- you can use the drops to double check meter's accuracy, and if the batteries or probe go dead you'll have a backup solution ready.

*another side benefit of using nutrients at 50% strength is that you don't have to worry about overfeeding, and overloading PPMs.

 

[1love1earth]

so what did you do about your pen/meter?

How did you keep the new one good?

I store it in "genesis storage solution", but I don't really clean it or anything, just rinse off and dip it in the storage solution.