How to know how much additives in hydro

9

967

Active member

• Oct 15, 2017

• #1

So I'm just wondering how does one know when to add more silica to their hydro rez? For example I'm growing ppk's, my rez EC drops, I add more base nutrients to bring back to desired level. But how am I supposed to know how much silica to add? (I'm not using Jack's...)

Is it a case of plants go through 5 litres water a day so I add whatever amount is recommended for that 5 litres to It?

How does one know if it's actually uptaking it and whether or not it's just building up to toxic levels? Is there even a toxic level??

 

E

Easy7

Active member

Veteran

• Oct 15, 2017

• #2

Suppose any nutrient can be toxic in excess. Calculate water added and nutrients for water added. People usually have ppm drop at a different rate than water. So some just get ppms and ph to normal. One reason I dislike hydro is the complications and expense if going thru all the gear.

 

Lester Beans

Frequent Flyer

Veteran

• Oct 15, 2017

• #3

Add the silica as per the instructions on the bottle. Easy peasy.

 

9

967

Active member

• Oct 16, 2017

• #4

Yeah that's what I do in the first place, with a fresh rez, but I have no way of telling how much silica has been used and how much remains in solution is more my point. If it uses 10% of the total water but only 5% of the silica it will slowly build up over time if I keep adding it back

Guess I'll just add it at rez change and let it slowly deplete...

 

Lester Beans

Frequent Flyer

Veteran

• Oct 16, 2017

• #5

It's best to change the res every week. Then there is no worry of any build ups.

 

9

967

Active member

• Oct 16, 2017

• #6

Every week? I run a with 50 odd litres or 15g or whatever that equates to, I'd be dumping more nutrients than my plants would be using... sounds costly!

Last change I did around 3 weeks but I keep additives fairly minimal to prolong life. Some people don't change at all for the entire grow

 

Lester Beans

Frequent Flyer

Veteran

• Oct 16, 2017

• #7

Costly or not, res change every week for best results. That's just how it's done.

 

E

Easy7

Active member

Veteran

• Oct 16, 2017

• #8

There is probably a calculation possible of equating ppm change versus water droppage.

Soil is a lot easier. Doesn't make sense running soil in a huge warehouse grow and the only size I'd find the trouble worthwhile for hydro.

 

Douglas.Curtis

Autistic Diplomat in Training

• Oct 16, 2017

• #9

967 said:

Every week? I run a with 50 odd litres or 15g or whatever that equates to, I'd be dumping more nutrients than my plants would be using... sounds costly!

Last change I did around 3 weeks but I keep additives fairly minimal to prolong life. Some people don't change at all for the entire grow

Click to expand...

I haven't dumped a flower rez, before the last 5 days, in over 10 years. You do need a ppm/ec meter to do it, and I highly recommend it for the best quality. Lucas has great information on res management methods for not dumping your res throughout flower.

Dumping is definitely a huge waste of nutes and water, unless you're using it for a veggie garden?

@967 The version of silica I add (pro-tekt) causes a rise in pH. I add silica the first week of flower and then watch the pH drop over the next week. Personally, I prefer the quality when I only add silica once. Should you want to, you can add it again when the pH has stabilized.

Other amendments are more of the same, though without pH changes it's more guesswork. You're basically looking to figure out how much they're using and only supply what they need.

 

9

967

Active member

• Oct 16, 2017

• #10

Thanks Douglas, that's what I want to hear. Ive been growing coco DTW for years, I have ph and ec meters and shit, but I used to handwater coco and rather than automate that, I kind of bastardized and adapted what I could to make a 4 site ppk. If it turns to shit I can always fall back on the coco. Just don't have any runoff in ppk to help avoid build ups of chems..

Cheers

 

Douglas.Curtis

Autistic Diplomat in Training

• Oct 17, 2017

• #11

My pleasure.

 

C

CaliNewby

Member

• Oct 17, 2017

• #12

I usually just follow the instructions on the bottle. Sometimes I wonder if the companies give the right dilution or would you say they "up"it a little to make us use more?

 

Douglas.Curtis

Autistic Diplomat in Training

• Oct 17, 2017

• #13

CaliNewby said:

I usually just follow the instructions on the bottle. Sometimes I wonder if the companies give the right dilution or would you say they "up"it a little to make us use more?

Click to expand...

Cannabis requires around 1/3rd to 1/4th as much nutrient/additive as most varieties of plants. You're most likely buying 2/3rds to 3/4ths more product and affecting your end flower quality negatively.

 

Only Ornamental

Spiritually inspired agnostic mad scientist

Veteran

• Oct 21, 2017

• #14

Regarding toxic levels of silica: Silicic acid is only soluble at about 120 ppm, everything above will fall out as silica gel and (with luck) redissolve once its concentration in solution falls below the 120 ppm. Stupid thing is, that when combined with nutrients (e.g. Mg, Ca, and metal trace elements and even P under certain conditions) it will form completely insoluble mixed mineral deposits. The advantage of this is that it can't build up toxic levels. It can only cause loss of other nutrients. Depending on the product, you also introduce other stuff and not pure silicic acid. Potassium is fairly tolerant at the applied levels whereas the other things... poor labelling practice makes that part unpredictable!