It's A Fuct World

[infinitescrog]

Should be OK in general, but I do have problems with the Hempy concept. Allows roots to sit in stagnant water, which can (and almost surely will) cause problems.

If you can't measure it, you can't manage it. Getting as much diagnostic equipment in your op as possible is always worth doing.

They drink the entire reservoir every day to 1.5 days so they arent in stagnant water for more than a day but I can see this being a problem when they aren't in flower I only have to water every 2 days, I have this sog going and I have two 5 gal. DWC vegging in a scrog going to put them in soon, and depending on results may or may not switch over to that.

And I am getting my hygrometer tomorrow!

Thanks for the advice!

 

[Al B. Fuct]

Hey Al, I do rockwool cubes in a 8x4' flood and drain with a 300L rez, so these questions will draw on your past experience with rockwool before you switched to fytocell (which is not available in my area):

OK.

1. Does algae that grows on top of rockwool cubes eat nutes and raise the pH in the cube?

Algae does eat a small amount of your nutes, but not enough to worry about. However, it's not the algae raising the pH, it's pathogens like pythium and fusarium, which are probably present due to overwet conditions, causing the pH to jump.This is indicative of root problems. You'll probably find dead and rotting roots if you look.

2. Are cube covers a good idea or is it better to just deal with the algae? - I am seeing some mold develop under the covers as they are not getting the air circulation. also have some mold on bottom of RW cubes later in flowering

A cover of some sort that blocks direct light but allows air circ is what you need.

3. When to water RW? - 50% saturated weight, 25%,...?

Somewhere between 25% & 50%.

4. Can you keep RW 75% saturated at all times if your rez is well oxygenated AND you use H2O2?

No. When RW is saturated, water won't move into it. Best to let the plant's transpiration and evaporation remove a significant portion of the water before you add more.

5. I have some difficulty managing the ideal EC in the cube, I am guessing due to cube sometimes running dry and perhaps too much nutes in rez. I run EC 1.6 in the rez, but pull EC 3.2+ later in flowering out of the cube with a syringe. Plants don't seem to mind too much, but the salt build up concerns me, should it?

1.6 EC is 1120ppm, kinda hot. 3.2EC is 2240ppm, which is well into cooked. It'd concern me a lot!

Sure you're probably right. There is also some credibility in the fact they would stand to lose sales from that info rather than gain.

Sooo… any RIU members interested in swapping your old rusty 600w coil ballast for a super sweet shiny purple DIMMABLE (!!) Lumatek, PM me!

If you have it, use it. You're unlikely to recover much of your outlay by onselling it- used ballasts don't normally have much resale value. If it blows up while still in warranty, get another one, bearing in mind that there may be a pro-rata warranty, where you may be expected to pay a portion of the replacement cost. Compare what you have to pay on the pro-rata against what you will spend on a new magnetic ballast.

I DO shake my head when I think of the EEs at Lumatek adding the dimming feature. WHY would you want to dim a horticultural light? Mood lighting, I guess...

They drink the entire reservoir every day to 1.5 days so they arent in stagnant water for more than a day but I can see this being a problem when they aren't in flower I only have to water every 2 days, I have this sog going and I have two 5 gal. DWC vegging in a scrog going to put them in soon, and depending on results may or may not switch over to that.

And I am getting my hygrometer tomorrow!

Thanks for the advice!

Your plants removing a significant portion of the water in the bucket in a relatively short period of time is your only saving grace. If the plants were smaller, transpiring less water and doing so more slowly, you'd be more likely to see problems.

 

[Bob Smith]

I've blown up a few dual arc bulbs using my digital dimmable ballasts, but regular HPS bulbs work fine on them.

The dimmable feature is nice for someone like me who can't move their lights in relation to their plants and doesn't want to shock plants coming straight from fluoro tubes to 2400 watts of light - starting them off at 50% really helps them ease into their new home.

 

[jojodancer10]

hay DR. Al ,just built a box hor my mom's under a 4 foot eight bulb flo. just wanted to say thanks and you were wright about everything. my 6 mom's are in hydro farm buckets. lol they took off like a bat out of hell. thanks al. i will put post pic's of my mom's before i take cuts

 

[Ferredoxin]

Al....... Thanks for all your knowledge over your countless posts. I am usually more of the trolling type, but every now and then a question pops up that I can't find a straight answer to. I am very well versed in plant physiology and soil culture, but I am new to the hydro scene. I am still trying to pinpoint a reservoir management strategy that is effective and easy. Work smarter, not harder right?

I dont employ your perpetual system, opting to instead grow fewer, larger plants. I have 16 grape stompers under 4 1000w HPS (4 per light) in a CAP Ebb & Gro system w/ hydroton. I am using GH nutes following the Lucas method (sort of....i am actually doing 3G/5M/15B ml/gal for the first 2 weeks of 12/12 before I take the Grow nutes out). I keep the reservoir at 40 gallons by topping off every day with fresh H2O (plants are using about 5 gallons per day right now...Day 11 of 12/12...flooding 4x per lights on and nothing in the dark). As you can imagine, my EC tails off rather quickly with each slug of H2O I add. I seem to get equally valid opinions about topping with either straight H2O or with nutrient solutions of various strength (Lucas says full strength, some say 1/2 strength, some say 1/2 strength every other day....). Either way, I would like to try to stretch out my reservoir changes to the longest interval as possible without sacrificing plant health.

Should I aim to maintain a target EC, or allow the EC to drop over time? What is an acceptable drop? Again, the Lucas method says to drain and refill the res after 1/2 the original volume has been added back. That would mean every 4 days for me, which seems a bit much. Any guidance you offer is appreciated....thanks.

 

[medicine21]

Thanks for the response, Al.

Algae does eat a small amount of your nutes, but not enough to worry about. However, it's not the algae raising the pH, it's pathogens like pythium and fusarium, which are probably present due to overwet conditions, causing the pH to jump.This is indicative of root problems. You'll probably find dead and rotting roots if you look.

No root problems here. I learned my lesson of overwatering 2 crops ago and I watered every second day in 5 day veg and first 12 days flowering. The cubes got quite light at some points (around 10% saturated) for sure. It gave good roots (never wilted) but built up my EC in the cubes over time.

A cover of some sort that blocks direct light but allows air circ is what you need.

I experimented with covers like this in side-by side without them, but I don't see a difference in the plants. Observed differences WITH the covers is no algae, higher EC, lower pH and mold later on. Not sure what else to cover with or if it's even necessary.

1.6 EC is 1120ppm, kinda hot. 3.2EC is 2240ppm, which is well into cooked. It'd concern me a lot!

It did concern me at first and in the past I would flush the cubes once a week, but now I am running with it and the plants don't seem to mind. I wonder if it's possible that it is build up that is not even used by the plants. The numbers tell me they should be burning, but I'm in W9 of flower and they are plumping up, probably another 10-14 days to go.

Another question. If you don't mind...

Have you noticed a big difference in yield in flood and drain setup when upgrading pot/medium size? I have ran 4'' x 4'' x 3.25" and 4x4x4" cubes side by side and saw no difference in plant or bud size.

 

[Al B. Fuct]

I've blown up a few dual arc bulbs using my digital dimmable ballasts, but regular HPS bulbs work fine on them.

Combination MH/HPS lights really are not necessary anyway, so no great loss.

The dimmable feature is nice for someone like me who can't move their lights in relation to their plants and doesn't want to shock plants coming straight from fluoro tubes to 2400 watts of light - starting them off at 50% really helps them ease into their new home.

meh... I put clones, which have been under fluoros for about 14 days, straight into the flowering room under 1000HPS with never a problem.

hay DR. Al ,just built a box hor my mom's under a 4 foot eight bulb flo. just wanted to say thanks and you were wright about everything. my 6 mom's are in hydro farm buckets. lol they took off like a bat out of hell. thanks al. i will put post pic's of my mom's before i take cuts

I hope fluoros are enough to raise your mums. If you're running a perpetual/rolling harvest system where you need cuttings every couple of weeks, you'll need a fair amount of light power to regrow them within that time span. I don't generally recommend fluoros for anything but clones, because they only need to be convinced it's daylight for 18-24h/day, instead of needing a lot of light for photosynthesis.

Al....... Thanks for all your knowledge over your countless posts. I am usually more of the trolling type, but every now and then a question pops up that I can't find a straight answer to. I am very well versed in plant physiology and soil culture, but I am new to the hydro scene. I am still trying to pinpoint a reservoir management strategy that is effective and easy. Work smarter, not harder right?

Yep.

I dont employ your perpetual system, opting to instead grow fewer, larger plants. I have 16 grape stompers under 4 1000w HPS (4 per light) in a CAP Ebb & Gro system w/ hydroton. I am using GH nutes following the Lucas method (sort of....i am actually doing 3G/5M/15B ml/gal for the first 2 weeks of 12/12 before I take the Grow nutes out). I keep the reservoir at 40 gallons by topping off every day with fresh H2O (plants are using about 5 gallons per day right now...Day 11 of 12/12...flooding 4x per lights on and nothing in the dark). As you can imagine, my EC tails off rather quickly with each slug of H2O I add. I seem to get equally valid opinions about topping with either straight H2O or with nutrient solutions of various strength (Lucas says full strength, some say 1/2 strength, some say 1/2 strength every other day....). Either way, I would like to try to stretch out my reservoir changes to the longest interval as possible without sacrificing plant health.

I'm not a fan of this Lucas stuff.

You should never add nutrient concentrate nor freshly mixed nute soln to an old tank of nutes. Use the nutrient mfr's instructions for mixing. If you follow the mfr's mixing instructions, you'll get the NPK ratio the mfr specifies. A partially spent tank of nutes may (for example) have half the N, 1/3 of the P and 2/3 of the K remaining. If you add nute concentrate or premixed nute soln to the tank, you're not going to get the mfr's specified NPK ratios. You may end up with more of one and less of the other. Ratios that are out of whack can cause the appearance of nutrient deficiencies, but they're not deficiencies at all. You wind up chasing your tail and cooking plants.

When topping up tanks, you might dip your TDS meter into the solution and add plain water until the TDS comes to the point it should be at, 1000ppm or so. The NPK ratios won't be at the specified ratios for a fresh tank, but you'll be shooting low instead of high. It's always better to underfeed than burn. You can recover a plant from underfeeding- you're much less likely to be able to recover a cooked plant.

Should I aim to maintain a target EC, or allow the EC to drop over time? What is an acceptable drop? Again, the Lucas method says to drain and refill the res after 1/2 the original volume has been added back. That would mean every 4 days for me, which seems a bit much. Any guidance you offer is appreciated....thanks.

It's preferable to maintain a target strength. Most nutrient mfrs will tell you something similar as regards changing the tanks when 50% of the volume has been replaced with plain water. If your nute strength is dropping precipitously when topping up, just don't top the tank up fully.

You might also consider a larger res tank. 5L per plant is is about right. I use 125L tanks with trays that hold 24 plants. The nute strength will stay constant, within about 10%, as the soln level drops, over a 2-week life of a tank of nutes. In other words, the plants are eating the nutes in a similar proportion to the quantity of water they're using. I don't have to top up at all, just add H2O2 every 3-4 days, then dump, clean & mix new sauce at the 2-week point.

 

[Al B. Fuct]

Thanks for the response, Al.

no worries.

No root problems here. I learned my lesson of overwatering 2 crops ago and I watered every second day in 5 day veg and first 12 days flowering. The cubes got quite light at some points (around 10% saturated) for sure. It gave good roots (never wilted) but built up my EC in the cubes over time.

Good that there's no root problems, but pH spiking upward is characteristic of pathogen issues.

Part of the TDS figure from the runoff is comprised of accumulated Mg & Ca redissolving and being carried out by the runoff. The problem is, we don't know just how much. If the plants are doing OK, I don't think I'd have as much basis for concern. Mg & Ca won't contribute to the usual excess-N nute burn.

I experimented with covers like this in side-by side without them, but I don't see a difference in the plants. Observed differences WITH the covers is no algae, higher EC, lower pH and mold later on. Not sure what else to cover with or if it's even necessary.

Was there airspace between the covers and the RW cubes? Mould tends to be inhibited by air motion. Might prop them up with 3-4 plastic swizzle sticks into the top of each cube.

It did concern me at first and in the past I would flush the cubes once a week, but now I am running with it and the plants don't seem to mind. I wonder if it's possible that it is build up that is not even used by the plants. The numbers tell me they should be burning, but I'm in W9 of flower and they are plumping up, probably another 10-14 days to go.

I suppose the proof of the system working OK despite the runoff figures is whether the plants are doing OK.

Another question. If you don't mind...

Sure.

Have you noticed a big difference in yield in flood and drain setup when upgrading pot/medium size? I have ran 4'' x 4'' x 3.25" and 4x4x4" cubes side by side and saw no difference in plant or bud size.

That's not an awful lot of difference in volume between the two. You really don't need much media volume unless you're growing big plants. If you are growing a small number for legal reasons and thus have to veg a bit before you flower instead of growing a large number of SoG 'lollipops,' you'll probably want about 4L of pot/media volume. My mother plants, vegged for months in some cases, will get a bit potbound by the time I retire them. They're in 175mm dia x 175mm tall pots (as is everything else), which are pretty close to 4L. My flowering plants don't even begin to get potbound by harvest time. I could use smaller pots and less media, but a SoG plant pretty much needs that 175mm circle for foliage space, so even with smaller pots, I don't think I'd grow a greater number of plants in each tray. Smaller pots would make it easier for plants to tip over when the buds get heavy. My trays are 900mm x 900mm- so it happens that 24x 175mmm pots fit very tightly in the trays and simply can't fall over.

 

[Ferredoxin]

I'm not a fan of this Lucas stuff.

You should never add nutrient concentrate nor freshly mixed nute soln to an old tank of nutes. Use the nutrient mfr's instructions for mixing. If you follow the mfr's mixing instructions, you'll get the NPK ratio the mfr specifies. A partially spent tank of nutes may (for example) have half the N, 1/3 of the P and 2/3 of the K remaining. If you add nute concentrate or premixed nute soln to the tank, you're not going to get the mfr's specified NPK ratios. You may end up with more of one and less of the other. Ratios that are out of whack can cause the appearance of nutrient deficiencies, but they're not deficiencies at all. You wind up chasing your tail and cooking plants.

When topping up tanks, you might dip your TDS meter into the solution and add plain water until the TDS comes to the point it should be at, 1000ppm or so. The NPK ratios won't be at the specified ratios for a fresh tank, but you'll be shooting low instead of high. It's always better to underfeed than burn. You can recover a plant from underfeeding- you're much less likely to be able to recover a cooked plant.


It's preferable to maintain a target strength. Most nutrient mfrs will tell you something similar as regards changing the tanks when 50% of the volume has been replaced with plain water. If your nute strength is dropping precipitously when topping up, just don't top the tank up fully.

You might also consider a larger res tank. 5L per plant is is about right. I use 125L tanks with trays that hold 24 plants. The nute strength will stay constant, within about 10%, as the soln level drops, over a 2-week life of a tank of nutes. In other words, the plants are eating the nutes in a similar proportion to the quantity of water they're using. I don't have to top up at all, just add H2O2 every 3-4 days, then dump, clean & mix new sauce at the 2-week point.

Excellent. I had that little voice in the back of my head telling me to follow the label rates...not sure why I thought this guy Lucas knows better than the scientists at GH. =/

So basically it is okay to let the res drop over time as long as a) there is enough volume to complete a flood, and b) the EC stays constant. I have been short-filling my 55 gal res to save on nutes and water, but it sounds like I will fill it all the way and just let it drop. 55 gals - 15 gals for a flood = 40 gals to play with, divided by 5 gals/day consumed = 8 days between changes. Easier for me, and better for my plants....I love it when that happens!

 

[Al B. Fuct]

sounds like a plan, Stan.

 

[medicine21]

Was there airspace between the covers and the RW cubes? Mould tends to be inhibited by air motion. Might prop them up with 3-4 plastic swizzle sticks into the top of each cube.

That's a good idea, I will give it a shot next time! Thanks.

You really don't need much media volume unless you're growing big plants. If you are growing a small number for legal reasons and thus have to veg a bit before you flower instead of growing a large number of SoG 'lollipops,' you'll probably want about 4L of pot/media volume.

In fact, this is exactly what I have to do. Moving away from 30 SOG plants per each 4x4' area, that has treated me so well thanks in part to your previous threads.

The plan is to convert to a 4 week perpetual. One 4x4' flood and drain doing 4 week veg. Two other 4x4 flood and drains doing 1-4 and 5-8W flowering. There would be 12 plants in each 4x4 shooting for 3oz/plant. I am currently doing almost an ounce per SOG plant with a 5 day veg.

During veg, the plants are Uncle Ben topped and the cuttings become clones. So the idea is to have a motherless perpetual with 48 plants. Not sure if that makes sense, since I have no experience cloning or growing big plants.

I was going to do it in 6" RW cubes (3.5L) volume, really for the lack of something better. Hydroton doesn't hold enough water for safety margin for me and I don't want to clean it, coco doesn't seem ideal for flood and drain, can't get fytocell and sure-to-grow look to be crap. What's my best bet for these bigger plants in a flood and drain?

 

[Indefinately]

Hey medicine Mary,
I flood and drain coco with no issues.
I lay a layer of floc (bottom 8cm) of my pot.

Works great for me.....

 

[Highhopes99]

Hey al, i went to my local hydro store to get some flock, there asking me if I want repelant or obsorbant rockwool flock.
Do you mix these two together for better drainage? I know you don't use flock for flowering anymore but I wanted to know if you were using a mix of theses two when you used to use it for flowering? You have written that flock holds too much water so this could help? Also I was at the hardwear store looking at insulation and came across rock fiber insulation. It looks exactly the same as rockwool slabs. Was thinking of trying test to see if it would work as well. Any thoughts? Thanks.. Nice to see you still kicking around.

 

[pdillo]

If you have it, use it. You're unlikely to recover much of your outlay by onselling it- used ballasts don't normally have much resale value. If it blows up while still in warranty, get another one, bearing in mind that there may be a pro-rata warranty, where you may be expected to pay a portion of the replacement cost. Compare what you have to pay on the pro-rata against what you will spend on a new magnetic ballast.

I DO shake my head when I think of the EEs at Lumatek adding the dimming feature. WHY would you want to dim a horticultural light? Mood lighting, I guess...

Thank you sir, think I'll go ahead will invest in a Digilux bulb and see how it treats me. Also went ahead and ordered a lux meter, sounds like a wise tool to keep on hand. Along with the dim feature on new Lumateks, there is also an overdrive (or SUPER LUMEN!!) setting… which is probably good for burning bulbs out a lot faster. I've just kept it on normal 600w output so far.

While we got ya here, thought I would bug ya about batwing reflectors. I'm thinking of making my own to fit over my cooltubes for a better rectangular spread (pretty much the same dimensions as a medium adjust-a-wing). Would you say common hardware store mill aluminum with a high-heat matte white paint job suffice? Or would it be a better idea to go ahead and spend the extra cash on the reflector specific 'german aluminum' material (shiny aluminum with dimples) from the hydro shop? I mean, aesthetically that would be less ghetto looking

Thanks mane!

*edit - actually neva mind, went to the hydro shop earlier and the price on the german aluminum was pretty fair, thats what I'll be using

 

[skiweeds]

On flushing: The only thing you really need to flush is your toilet. There's no particular need to flush or leach cannabis plants before harvesting, but you can do it if you want. The plants store about 2 weeks worth of nutes, so you can safely give plants plain water, no pH correction needed, in weeks 6-8.

'Clearex' is completely unnecessary and falls into the dreaded 'magic sauce' category, that is, things that your local hydro shop are happy to take your dough for that won't really do anything. Nothing but time will cause plants to consume the remaining stored nutrients.

just curious, why would you not want to flush plants? i notice when i flush my plants the smoke tastes much better. i have harvested a few plants without flushing(same strain) and the smoke tasted like chemicals. i know a flush isnt needed, but shouldnt flushing be a requirement to grow premium dope since it improves the flavor?

im more of a soil grower myself. im new to hydro and just starting with a small aeroponic system. thanks a lot for this thread. lot of good info. +rep!

 

[pdillo]

i notice when i flush my plants the smoke tastes much better

haha, good luck convincing al of that! you might want to go ahead and bring up the importance of a 'good cure' while your at it

 

[hellraizer30]

Excellent. I had that little voice in the back of my head telling me to follow the label rates...not sure why I thought this guy Lucas knows better than the scientists at GH. =/

So basically it is okay to let the res drop over time as long as a) there is enough volume to complete a flood, and b) the EC stays constant. I have been short-filling my 55 gal res to save on nutes and water, but it sounds like I will fill it all the way and just let it drop. 55 gals - 15 gals for a flood = 40 gals to play with, divided by 5 gals/day consumed = 8 days between changes. Easier for me, and better for my plants....I love it when that happens!

lucas works good for young plant but as soon as they get bigger you will run into a def. and lucas swears by not useing supliments and thats BS GH has a online nute
calculator to custom build a feeding program. if you mix 1300ppm in 55gal of water and a day later its 40gal and 1400ppm your going to add back water to get back
to the 1300ppm but at the same time, if this is the case then I believe your ppm is to high to start with. If you start at 1300ppm and lose 10gal and its still 1300ppm
then I think its a perfect ratio, now plants will take more or less through there life span so get a calander and chart every feeding and change so next time you can follow
or correct your feeding. I use 1300ppm as a nonfiction number.

 

[jojodancer10]

hello family, DR. Al B. Fust, got a question for ya, i dont have much room so i built a home made box that's 4 feet long, 4 feet tall and two and a half feet wide. i had a t5 8 bulb light from my first grow about 2 years ago. i have been studing your style and i have came to the point that i will take cuttings from my mom's every 8 weeks. will the moms be ok under the flo's? or do i need to spend more money on my light bill? what size light system should i get if i am to spend money? a 150, 250, 400 or 600 watt light for 24sqf

 

[Ferredoxin]

My PPM has stayed consistent from day to day. It only drops when I add water back to top off. I am just not going to top off now.

 

[hellraizer30]

My PPM has stayed consistent from day to day. It only drops when I add water back to top off. I am just not going to top off now.

then it sound like you found that sweet spot