Hi

Got my system nearly finished now, a 9 pot RDWC with a 64 litre control tank.

I am yet to fill it and therefore do not know how many litres it will hold (got rough idea)

I am confused about topping it up, flushing, adjusting levels, especially since it is a large amount of water.

What is the simplest method ?

Do i just make up a large stable mix and keep it in a separate bucket ? Or

If the system needs ph/ec adjusting do i just add it to the control bucket ?? Or do i add an adjusted made up mixture ??

If i flush all the system do i need to make up my solution then add it, or can i just add water then nutes, then ph ??

Whats the easiest method ?

Cheers

Hi m8ty,
I have not yet grown but I am going along the same lines as you with RDWC. I will be using the LUCAS method of growing (Do a search for lucas on google and it will explain the best way to control nutrient levels etc..) Basicaly you use GH nutrients (Only Bloom and micro, not all 3) and control the nutients in the res at 1300ppm (lower in the early stages of growth), at a set ratio between the two nutrients, depending on the stage of growth. This gives the plants all they need and it seems quite simple to follow. I posted some links on the subject but they were removed as they were classed as spam, so if you dont find what you are looking for on google let me know and I will try and help more.



Regards cain1.

Hi Mate

Will have a read up on that now, i got my nutes all ready, Ionic Grow/Bloom/Boost. It says to add 7ml per litre.

So if i fill up to 200l (16l each bucket(x9) and res) i will need to add 1400ml/1.4 litres !!!!

That seems hell of a lot !!

That does seem a hell of a lot! Regardless of the size of the res, 7ml per litre of grow nutes??

hey takeiteazy

have you got an ec meter ? really need one of em mate

you also dont need to have a high ec in them buckets mate, i never go over 1.6 in the full grow

obv you wont be filling the buckets right up, prob be about half full
so that means if your res is sitting at the same level as the buckets the water level in the res will be at the same level through the whole system

mines is roughly only half filled to what it can actually hold

Yes mate got a bluelab on its way along with a ph pen.

As i stated above i have ionic grow/bloom/boost and have the feeding schedule info for it.

The problem is is just mentions 7ml/l for the grow/bloom and 1ml/l for boost.

What i am trying to find are the recommended EC levels for various stages of growth for these nutes ?

I know to start low and work up but that's about it...

Cheers

your plants will tell you mate when they getting hungry

also checking your ec alot with the ec meter will give you an idea if there needing more/less nutes

Hi takeiteasy,
Her is an example of how to add back nutrients using the lucas formula. I Copied his off the ask Lucas site so thanks o them for this example.

the markup formula uses the target tds, and a current tds, to calculate the percentage difference, then use that percentage to multiply against the 8ml that produces the target

so if for example the target is 1300 and the current is 900 with a 50 gallon res it maths out like this

target/current-1*8*Res Size=how many ml of nutes to add to the res

1300/900-1*8*50=178 total ml of nutes to add to the res

phew, you forced me to remember that, thanks

this formula is much more accurate than a 33% addback. It is based on markup math, and produces a nute dosage that will tend to be slightly too much, the TDS will be overshot

the inverse formula, using markdown math, produces a more conservative estimate

it goes like this
1-(current/target)*8*res size=total ml of nutes to add to res

what counts is to get enough nutes added back to get up to the target TDS, of 1300-1400

the two formulas are predicting that to raise TDS 400 points will take between 125 to 172ml of nutes

once you do it once, it will be the same the next time... you just need to get into the ballpark, or raise TDS in steps..

Hope this helps,

Regards cain1.

PS I also think the nutrients are added per american gallon NOT per litre.

Realised that its in Gallon so another conversion, think i will just stick to EC levels to start of. Start of off at 0.4 and take them upto 1.0

Check and see if they are using water or nutes and either top up with a stronger/weaker mix accordingly.

Just want a ball park ec level for when in full veg/bloom really and i will then work up to it.

Cheers guys.

Hi takeiteasy,
Try these nute strengths, they are explained a bit better here.

General Hydroponics Flora Series Feeding Strategy - Lucas Formula

G-M-B (Grow-Micro-Bloom)
0-5-10 - For Vegetative cycle (18/6)
0-8-16 - For Flowering cycle (12/12)

The numbers above indicate the number of milliliters (ml) of Flora Grow, Micro or Bloom formulas that I use in one gallon (US Liquid) of nutrients.

You will notice I dont use any of the Flora “Grow” formula, do not need to, the Flora "Micro" provides plenty of Nitrogen.

There are two ways to work with this formula:

1. Top off the reservoir daily using a pH corrected water solution as required to maintain full reservoir level. After adding back an amount of water equal to the amount of your reservoir capacity you should change the reservoir and put in fresh solution.

2. Top off the reservoir daily using a pH corrected 100% strength nutrient solution as required to maintain full reservoir level. Continue to use this nutrient solution without dumping the tank unless the PPM rises above acceptable levels.

Between vegetative and flowering cycles you should dump your nutrients, then flush (possibly with Clearex) to remove salt buildups, then change to the other feeding program. Always shake your GH nutrient bottles before using them!

For young plants, just transplanted into the hydro setup, give them 50% strength nutrient mix to prevent overfeeding them while their young. Gradually bring up the mix to full strength as they grow over the next few weeks or so.

The lucas formula is normally intended for use with RO or near 0 PPM water. (RO = Revers osmosis, you can get a 3 stage unit for 50 quid)
NOTE: The Lucas formula eliminates the need for Epsom salts to correct (Magnesium) Mg deficiencies in most normal feeding programs recommended by manufacturers. Cannabis needs a lot of Magnesium to thrive.

The Flora Micro is providing the Nitrogen and the Magnesium in the proper balance, thus there is no need for the Grow formula and little or no room under the maximum acceptable ppm limit of 1600 @ 0.7 conversion.

Calculated EC/TDS levels:

EC microsiemen:
0-4-8: 946 µS
0-5-10: 1184 µS
0-8-16: 1894 µS

TDS @ 0.5 conversion:
0-4-8 = 473 ppm
0-5-10 = 592 ppm
0-8-16 = 947 ppm

TDS @ 0.7 conversion:
0-4-8 = 663 ppm
0-5-10 = 829 ppm
0-8-16 = 1326 ppm

Addback Calculator - (For Advanced Users)

Say you were running the 0-8-16 formula, at 0.7 conversion with a 22 gallon res. When you first fill it up, your ppm will be around 1330.

Now you have been growing for a week, and some of the water has been taken up by the plants, some has evaporated, and now your res is at 947 ppm. You need to get your ppm from 947 to 1330. Here is the equation:

((target - current) / target) * 8 ml per gallon * res gallons = Flora Micro (ml) double this figure to get Flora Bloom (ml)

Example:

((1330 - 947) / 1330) * 8 * 22
(383 / 1330) * 8 * 22
0.3 * 8 * 22 = 53 ml Flora Micro

53 ml Flora Micro, double that and you get 106 ml Flora Bloom. So 53 ml Flora Micro and 106 ml Flora Bloom to add back to your 22 gallon res to get you from 947 to 1330.

Using Hard Water GH Micro

I had been experimenting with using the Hard water Micro as a substitute for the normal Flora Micro, this to account for my hard 350 PPM water and the lack of a large enough RO filter at the time. It has worked well for me. I just kept my reservoir below 1150 PPM @ .5 conversion and its all good.

One tip - do not pH down this stuff, the hard water micro will drop pH gradually over the next 24 hours, for example I mix up a batch, it is at like 6.2, the next day, its at 5.6-5.8 after running in the system for a while. If I pH downed that to 5.7 before putting it in the system, it ended up as low as 4.8-5.2 by the next day.

My conclusion, the hard water micro was buffering the alkaline crud in my water, it just doesnot do it ASAP fast like the phosphoric acid.

Again taken from another site not my work but is good info for us beginners.


Regards cain1.