Cooked leaves - nute prob?

[Al B. Fuct]

That was teaspoon not tablespoon, 2 tablespoons will be way too much.

 

 

mmmmmkay- dump the tanks?

[Al B. Fuct]

Just weighed 1 TSP & 1 TBS of MgSO4 xtals to get an idea of how far wrong I've gotten it.

 

1 TSP weighs 4.6g and 1 TBS weighs 13.4g, so I've put in about 2.9x what you've recommended, 26.8g/125L instead of 9.2g.

 

Costs about $30 to dump the tanks and mix them up again. Worth doing? These tanks will normally be dumped in 15 days.

[Luke Skywalker]

The PK could be at fault, but usually thats added at 3 weeks before harvest, though as your in a sog system you may well be only doing a 6 week bloom? PK supplimentation can give good results but I find that the manufacturers almost always recommend far too much, thus causing a lockout down the line with calcium phosphate. Notice any cloudiness in the nutrient when you added it? It's a reasonably regular thing to hear of people adding PK at what seems like a reasonable rate and then discover the plants slowly develop a yellowing from bottom up.

 

PK is highly alkaline, as you would expect from the K proportion of the mix. The P205 is indeed an acid, but is outweighed by the highly alkaline potassium oxide. Keep in mind that these are relative concentrations of what they would be if they were in this form too, not the actual chems involved. You may have a whole pile of other substances in there as labelling typically converts the % to the most available plant form, regardless of what's actually in there.

 

What's the tapwater e.c. like raw? And what kind of e.c. jump did you see after adding the PK to the 1400ppm of canna?

 

A good idea is to have a liquid pH test kit to occasionally test against the electronic one.

 

What's the direct runoff from the pots (before it remixes with the res) pH and e.c. like?

 

Oh yeah, and what conversion factor are we talking with the 1400ppm? 500 or 650 or 700 scale? Cos that can make a big difference to the actual amount of nutrition in there. I really dislike ppm readings as they're almost always a quick way to confuse people. E.C. is the actual measure your taking, ppm is just a conversion factor.

[Chato]

Is it MgS041H20 or MgS047H20?

 

I add 1Tablespoon to 20L of water with no ill effects but thats of the first type which is usually found in chemist or supermarkets epsom salt varities, i've recently gotten some of the second type i mentioned, direct from a chemical supply company an i will be using much less.

 

I also think the pk is most of your prob, i'd go 1ml/L.

 

peace

c

[Tom]

Costs about $30 to dump the tanks and mix them up again. Worth doing?

Considering the worth of the plants I would and it sounds like you may have a couple of other problems with the nutrients as well, I would also give them a flush in between to rinse the medium out. I personally feel that Canna have dropped behind the other brands when it comes to growing mj, my favourite brand at the moment is Growth Technologies "Optimum" but I intend to give the Dutch Master Gold a try next as I've been hearing a lot of good things about them.

 

[torana2000]

but I intend to give the Dutch Master Gold a try next as I've been hearing a lot of good things about them.

 

 

Ill be giving both canna and dm gold a run side by side in next couple months so ill see how good each is to the other.

[Al B. Fuct]

The PK could be at fault, but usually thats added at 3 weeks before harvest, though as your in a sog system you may well be only doing a 6 week bloom?

 

8 weeks.

 

PK supplimentation can give good results but I find that the manufacturers almost always recommend far too much, thus causing a lockout down the line with calcium phosphate. Notice any cloudiness in the nutrient when you added it? It's a reasonably regular thing to hear of people adding PK at what seems like a reasonable rate and then discover the plants slowly develop a yellowing from bottom up.

 

Yes, I do see cloudiness when adding PK, but that dissipates quickly. I usually add it with a garden hose filling the tank, so it is mixed in rapidly.

 

PK is highly alkaline, as you would expect from the K proportion of the mix. The P205 is indeed an acid, but is outweighed by the highly alkaline potassium oxide. Keep in mind that these are relative concentrations of what they would be if they were in this form too, not the actual chems involved. You may have a whole pile of other substances in there as labelling typically converts the % to the most available plant form, regardless of what's actually in there.

 

Gotcha.

 

What's the tapwater e.c. like raw?

 

The Truncheon usually doesn't register on plain tapwater. Its bottom range is 140ppm. However, 5ml of Canna Flores A & B in 10L distilled water (from my dehumidifier) registers between 140-200. The same in 10L tapwater is 320ppm. One could thus surmise that the tapwater is about 120ppm.

 

And what kind of e.c. jump did you see after adding the PK to the 1400ppm of canna?

 

Jumps to about 1650ppm with 250ml in 125L.

 

A good idea is to have a liquid pH test kit to occasionally test against the electronic one.

 

I now have 2 working pH meters of different makes (a pHTruncheon & a Eutech pHScan 1) and calibrate them in the same ref solns. If they agree or are relatively close (+/- 0.1), I feel pretty confident.

 

What's the direct runoff from the pots (before it remixes with the res) pH and e.c. like?

 

Depends. I don't flush the rockwool floc before dropping rooted RW cubes in it- it will remain too wet for young plants with small root systems. It's practical to flush cubes, but not a 8" pot of floc. For the first 2-4 wks, RW floc will cause the pH to jump up a bit until any remaining limestone dust is flushed out. So, in wk 1, a 5.5 soln will drain out at 5.7-5.8. The jump reduces over the following weeks until abt wk 4-5 when the drain pH is about the same as that going in.

 

Oh yeah, and what conversion factor are we talking with the 1400ppm? 500 or 650 or 700 scale? Cos that can make a big difference to the actual amount of nutrition in there. I really dislike ppm readings as they're almost always a quick way to confuse people. E.C. is the actual measure your taking, ppm is just a conversion factor.

 

I use a Truncheon nute meter. It is calibrated in PPM, EC & CF. Unknown what conversion table they apply.

[Al B. Fuct]

oh, and I'm feeling pretty hopeful about the Fytocell stuff. May sort out some probs. Doesn't have the effect on pH as does RW floc.

 

I've decided to dump half of tank 2, which has the PK in it. I'll add back in 50% of the nutes I normally would add when mixing up a fresh tank. This will cut the PK concentration to 1ml/L without dumping the whole tank. Will cut the Mg concentration by half as well.

 

I'm feeling sorta OK about the 26g of MgSO4 (grocery/pharmacy type) in the other 125L volumes after sniffing around a bit on some commercial Mg additives. Will cut the dose in the next batches of sauce, tho.

 

Thanks folks.

[SukonmiSkunk]

hey al... this is a great page to refer to when dealing with issues...

 

nute probs..

 

looks to me its an over dose of Potassium ... have a look see what you think...

 

sorry for not getting to it earlier.. im working class scum these days.. and havent been around a lot during the week...

[Al B. Fuct]

SS, thanks for that. I think you're right. Looks just like the "Potassium (K) Toxicity" image.

 

It's probably the PK. I'll back it down to 1ml/L and if I still see the prob, half that again.