DWC Rez Addback Methods

What do you do and why?

Top up with plain water every day?

Top up with nutrient water every day?

Let the level drop down adding nothing until the next rez change?

I heard that roots left above the water line will convert to air roots within 6 hours of exposure to air, and once you refill and raise the water level, you will "drown" them.

Currently I'm mentoring a DWC system that holds 5 plants, 40 gallons of water when "full" (to the bottom of the net pots). Over the 10 days between changes, at peak water consumption (weeks 5-7 flowering) the solution level drops about 6" over the 10 days between changes, and is then emptied totally and brought back to the bottom of the net pots with new solution. Does anyone else use this method?

I see a lot of people use the crazy addback calculator for the Lucas formula, and a lot of other people add back plain water or RO every day/few days to keep the system full, but how do you track your EC movement when your diluting your rez every day?

I will tell you what works for me, which isn't perfect by any means, but like I said it works for me. I store my plan "top up" water in a 5 gallon water cooler bottle, and every time that I use two of them, I add back 5 gallons of nutes. I basically use the lucas formula, but with 2.5ml of grow per gal, mainly because I run perpetual out of one res. I Am now looking at setting up so the last 2 weeks they are in, they will be in a separate "zone" and only get plain water.

Hydrolized said:

What do you do and why?

Top up with plain water every day?

Top up with nutrient water every day?

Let the level drop down adding nothing until the next rez change?

I heard that roots left above the water line will convert to air roots within 6 hours of exposure to air, and once you refill and raise the water level, you will "drown" them.

Currently I'm mentoring a DWC system that holds 5 plants, 40 gallons of water when "full" (to the bottom of the net pots). Over the 10 days between changes, at peak water consumption (weeks 5-7 flowering) the solution level drops about 6" over the 10 days between changes, and is then emptied totally and brought back to the bottom of the net pots with new solution. Does anyone else use this method?

I see a lot of people use the crazy addback calculator for the Lucas formula, and a lot of other people add back plain water or RO every day/few days to keep the system full, but how do you track your EC movement when your diluting your rez every day?

Click to expand...

hydrolized: tap water to the fresh water rez as it is used automatically sometimes 5 gallons a day of fresh tap. nutes = 1/4 strength 1 part every 10 days or so... with this method the water to nutrient balance is perfectly stable so no wacky ph swings, etc. enjoy!

the float valve is pretty critical and i think costs 12.99 or something.

you can adjust if needed, but i havent had to.

You are doing things just fine. The line of nutrients used will vary the time between rez changes slightly, but it sounds like you are on point. When the water level drops the roots do not change and once topped back up again die. What actually happens is when the water level is dropping, the roots are encouraged to grow and they will!

It is still extremely humid inside the bucket even as the water level is dropping, the roots suspended in this humid air are absolutely loving it! Assuming the levels are not dramatically low and in turn accumulating a toxic feed level. This brings us to topping up. If the water level is so low that it needs a topping off, then you might as well refresh the whole system is my thought. Only towards the end of flowering when reducing the total feed in according to taste preferences would I ever recommend topping off with plain water. Nutrient mix should be applied correctly, although this is always easier said than done. Which is why at times the plain water top off can help. Never understood the topping off with additional nutrients myself, so hope someone who does this with success can stop in and give us the scoop.

Want to add, nutrient regime would also play a critical role in various systems. Sure all to work just as well.

Hydrolized said:

What do you do and why?

Top up with plain water every day?Perfectly fine doing this.. This is exactly what I did on my second grow. If your plants are heavy feeders then they will show signs of deficiencies during the latter parts of the nutrient change cycles. Though is they are very light feeders they will so absolutely no signs of deficiencies and grow very happy.

Top up with nutrient water every day?I love this method. Aside from the fact that it really makes you feel like an accomplished botanist I personally feel that it will bring out the very best in your plant. Two ways to do it: The first would be maintaining the level to a predetermined set TDS and pH while still following up with weekly changes. The second would be identical to the first with the main exception being that you will not change the nute solution at all! Though this method is for experts and requires not only knowledge of the add back formula but also a good knowledge plant symptom prevention as to know if you are experiencing any deficiencies due to over or under feeding of any specific elements.Also highly economical by ways of nutrient conservation.

Let the level drop down adding nothing until the next rez change?
Worst thing to due. The nutrient salts will start to accumulate and become toxic. The concentration of the nutrient solution will more then likely double if not triple your PPMs. This may shock your roots indefinitely.

I heard that roots left above the water line will convert to air roots within 6 hours of exposure to air, and once you refill and raise the water level, you will "drown" them.
You'll want the water line just under the net pots until the roots make their way into water. After that you will want to drop the water line a few inches. The high humidity in the res will keep the roots very happy. You never want fully grown roots completely saturated. It's all about keeping them happy! A powerful air pump and good air diffuser are a must! Though some may have mixed opinions on this.

Currently I'm mentoring a DWC system that holds 5 plants, 40 gallons of water when "full" (to the bottom of the net pots). Over the 10 days between changes, at peak water consumption (weeks 5-7 flowering) the solution level drops about 6" over the 10 days between changes, and is then emptied totally and brought back to the bottom of the net pots with new solution. Does anyone else use this method?
This if fine. This is exactly how my second grow went. Although letting it drop so low increases the nutrient salinity so long as you haven't experienced major problems you are okay. But this may play a role in your overall harvest. Might seem like a chore but I recommend you top every 2 days if you think everyday is tedious. May also help dilute any salt buildup on your roots. (You see with add backs this will not happen because you constantly maintain the PPMs in the solution without letting them become to concentrated.)

I see a lot of people use the crazy addback calculator for the Lucas formula, and a lot of other people add back plain water or RO every day/few days to keep the system full, but how do you track your EC movement when your diluting your rez every day?
The add back is simple if you follow the formula template. But I won't act as if it's all that easy because I remember when it used to elude me back in the days. As for plain tap water and RO water it will depend on the user. My tap comes out at 70PPM so I can almost immediately apply this to my plants but I like to wait for a few hours to let the chlorine evaporate. Some people on the forum have reported an initial PPM of 300 or more. That's a pretty wild swing there. You would want to look into your own starting TDS level. As for tracking your running EC level I would purchase a 24/7 TriMeter. They are great. The probes are constantly submerged into the solution. This way you can just look at the display mounted on a wall outside the growing area if you'd like it set up that way. Also a TDS drop will indicate the plants are feeding as well as a pH increase. Where as a pH drop may indicate the plants are releasing nutrients back into the solution telling you the juice was too strong to begin with TDS increase will normally follow.

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Here is the formula for your 40 Gallon rez:
Lets assume you don't use the exact 40 gallons since the water level is right under the net cups. So let's say 35 gallons. We would also assume you are using HID lighting as to use the 8/16 ratio for micro and bloom. If you were using fluorescent lighting which is less powerful then you would want the 5/10 ratio.

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

Say you want your TDS at 1500PPM and your current is 1100PPM

P.E.M.D.A.S = (1)Parenthesis / (2)Exponent / (3)Multiplication / (4)Division / (5)Adding / (6)Subtraction
((1500 - 1100) / 1500) x 8 x 35
(1500 - 1100) 400
(400 / 1500) .27
.27 x 8 = 2.16
2.16 x 35 = 76
76ml Flora Micro
152mL Flora Bloom (Double the Flora Micro mL for your Bloom.)
When using pH UP or DOWN your total PPM will fluctuate.

Once you use it a few times it'll become second hand nature. Hope this helps.

I jumped in on this thread because I personally feel DWC is the very BEST growing method. New variations on this method are being created everyday

Hydrolized said:

I heard that roots left above the water line will convert to air roots within 6 hours of exposure to air, and once you refill and raise the water level, you will "drown" them.

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You heard wrong

Ideally, what you're looking for is the ideal EC for your plants. Currently I keep mine at about 1.2 for most of the grow with a pH of 6. The EC stays level and the resevoir slowly drops. When it gets past a certain point (every 2-4 weeks for me) I drain off everything that's left, put it in the garden and start again with a fresh solution.

If you keep the EC and pH at reasonable levels you should never see any signs of deficiencies.

The air roots/water roots myth is complete nonsense.

killer thread.......

i run single 5 gal buckets for my plants. I mainly top up with only plain water. Some of my strain are quite thristy, and require more, so i'll top up with a mild solution of nutes.

but more so then not....im a topper with plain water !

hehe, I go about it my own unconventional way(of course), but it works for me, I simply do not top up, I let the water "run out" or severely drop, down to where there is only about an inch or two of water left and the uptake and feeding tubes are barely dripping any water out out to the plant, they still have just enough water in the bottoms of the buckets to maintain hydration of the plant and the air pump is still bubbling in the bottom of the bucket providing oxygen. Drain all the buckets, clamp the hose, refill rez with fresh water and nutes, unclamp.

The water and nutes are replenished once a week regardless if it needs it or not.

In fact, in one of my grow guides they suggest backing off the water levels a bit so that it helps promote stronger and faster more abundant root growth.

SumDumGuy wrote:The second would be identical to the first with the main exception being that you will not change the nute solution at all! Though this method is for experts and requires not only knowledge of the add back formula but also a good knowledge plant symptom prevention as to know if you are experiencing any deficiencies due to over or under feeding of any specific elements.

This is the method I use, as described above and believe me I am no expert. If I get even the slightest hint of a problem. I flush. I then "reset" the nutes as normal, never going over what is recommended.

SumDumGuy said:

Here is the formula for your 40 Gallon rez:
Lets assume you don't use the exact 40 gallons since the water level is right under the net cups. So let's say 35 gallons. We would also assume you are using HID lighting as to use the 8/16 ratio for micro and bloom. If you were using fluorescent lighting which is less powerful then you would want the 5/10 ratio.

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

Say you want your TDS at 1500PPM and your current is 1100PPM

P.E.M.D.A.S = (1)Parenthesis / (2)Exponent / (3)Multiplication / (4)Division / (5)Adding / (6)Subtraction
((1500 - 1100) / 1500) x 8 x 35
(1500 - 1100) 400
(400 / 1500) .27
.27 x 8 = 2.16
2.16 x 35 = 76
76ml Flora Micro
152mL Flora Bloom (Double the Flora Micro mL for your Bloom.)
When using pH UP or DOWN your total PPM will fluctuate.

Once you use it a few times it'll become second hand nature. Hope this helps.

I jumped in on this thread because I personally feel DWC is the very BEST growing method. New variations on this method are being created everyday

Click to expand...

Try this

Super's addback calculator (Lucas)
http://docs.google.com/fileview?id=...mMtN2ZlNi00MGFhLTkyNWEtYmRlODkzNDU1OWZh&hl=en

HybridHydro said:

This is the method I use, as described above and believe me I am no expert. If I get even the slightest hint of a problem. I flush. I then "reset" the nutes as normal, never going over what is recommended.

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You my good sir on on the road to being a botanist You'll be surprised how many people ride the wave till the very last second and say "WTF happened to my plant". You are very smart to flush when any inkling of a doubt occurs..

superusa said:

Try this

Super's addback calculator (Lucas)
http://docs.google.com/fileview?id=...mMtN2ZlNi00MGFhLTkyNWEtYmRlODkzNDU1OWZh&hl=en

Click to expand...

Ha, You are the man!!
Thank you SuperUSA. I never knew this existed. Very nice find indeed!!!

MAZEinaHAZE said:

killer thread.......

i run single 5 gal buckets for my plants. I mainly top up with only plain water. Some of my strain are quite thristy, and require more, so i'll top up with a mild solution of nutes.

but more so then not....im a topper with plain water !

Click to expand...

That's a very nice specimen you have there

Hydrolized said:

What do you do and why?

Top up with plain water every day?

Top up with nutrient water every day?

Let the level drop down adding nothing until the next rez change?

I heard that roots left above the water line will convert to air roots within 6 hours of exposure to air, and once you refill and raise the water level, you will "drown" them.

Currently I'm mentoring a DWC system that holds 5 plants, 40 gallons of water when "full" (to the bottom of the net pots). Over the 10 days between changes, at peak water consumption (weeks 5-7 flowering) the solution level drops about 6" over the 10 days between changes, and is then emptied totally and brought back to the bottom of the net pots with new solution. Does anyone else use this method?

I see a lot of people use the crazy addback calculator for the Lucas formula, and a lot of other people add back plain water or RO every day/few days to keep the system full, but how do you track your EC movement when your diluting your rez every day?

Click to expand...

Ok ill do my best to explain what i do and why.

First off i use a RDWC, capacity is in the range of 40 gallons. The entire system is changed every 14-21 days depending on when the water loses its PH buffering.

Lets introduce serveral scenarios here to explain whats going on. its day 7 after the water change. the plants have used approximnatly 20 gallons of water and its time to top it off.

the first thing i do is take stock of the PH and PPM.

PH = 6.5
PPM = 1300

The PPM in this scenario is higher then my desired of 1150ppm. i would usually add straight water to bring the PPM number down but my ph is too high. My PH usually has a gradual rise in reading so long as in not hammering them with nutrients. So its 6.5 here and i know i want it to around 6 or 5.5. Ill mix in a little PH DOWN in with the add back water making sure the PH reading in the add back water is LESS then the reading in the reservoir to bring the PH down.

Next scenario gets a little more complicated.
its day 14 after the water change. the plants have used approximatly 10 gallons of water and its time to top it off.

I take stock of PPM and PH

PH = 4.0
PPM = 700

ok things are going to get sticky here so bear with me. so the PH is down to low and the PPM is down as well. Well since the PH of water is 7.0 we know that that will raise the PH with out adding any PH UP to the mix. How much nutrients to add well that my friends is the million dollar question.

The easiest way i have found is to do this. Take a measure dose and add it to your system that is FULL (i cannot express how important this is, your system better be full) with fresh water taking stock of the water PPM to start. then add the dose lets say 25ml.

Fresh water = 100ppm
fresh water + 25ml = 250ppm

Now this gives me a ratio. 25ml = 150ppm

My reservoir is sitting at 700 ppm and i want it at 1150. So you use the ratio!

1150 desired ppm
-700 actaully ppl
450 desired rise in PPM


450 / 150 and you get your conversion factor of 3


so then 3 / 25 = 75 ML

add the 75 ML of nutrients to your mix and youll be really really close to 1150. BTW when using all of these numbers always err on the side of caution better to be to low then too high in my opinion. Once you figure out the amount to add. add it into the add back water pour it into your system and then recheck the PH. the nutrients will drop the ph of the add back water so this is important. if its not where i want it then and only then will i add PH UP into the mix. The desired effect here is to not add the PH UP and Down unless absolutly necessary.


sorry for the Tome hope this helps YMMV!!

Hazy

SumDumGuy said:

Ha, You are the man!!
Thank you SuperUSA. I never knew this existed. Very nice find indeed!!!

Click to expand...

It didn't exist lol I built it in excel for a friend, and then realized alot of people might benefit from it

superusa said:

It didn't exist lol I built it in excel for a friend, and then realized alot of people might benefit from it

Click to expand...

Nice. Now this is a very real addition to the Lucas community. Hot!

Well this is a bit odd but yet another "It works for me"

I've only been doing DWC for about 6 months (I am so sick of Pro Mix) and I kept reading about not changing your solution out that I wanted to try. I have been doing a full strength add back with no flushing. Just cut down 3 small ones that did great. They flowered for 10 weeks in the same solution. Been doing it for a few months now.

Now who knows if its water, nutes, rez size, plant uptake, medium (still working on that) But by luck maybe I just hit the right "numbers" some how. I'm still dialing this in. Bigger air pumps for 4 buckets, gonna upgrade 4 more soon. AC vent open this summer. And a large % of screw ups were my own doing, so with a bit more experience I think I can knock this out.

But by all means flush when needed, I have had a lil bit of root rot.

Some growers have gone over a year and never dumped their rez. It can be done. I don't see any reason anybody would need to dump their rez mid-grow; throwing out a lot of nutes, unless there was a problem mid grow.

Plants don't shit, well they do but it's called air and bark. The only thing in your rez is what you put in it.

I am very new to hydro so please show me what I am missing. If your plant is "eating" nutes and water at the same rate wouldn't you want your add backs to be at the same EC as the bucket?

I am feeding a GHS Cheese at 1.9 EC using 3/4 strength GH Flora series "transition to flowering" (2-2-2). I drained and refilled 2 days ago and have added back 1.5 gallon of nute solution and EC is staying at 1.9. pH has dropped .2

Maj.Cottonmouth said:

I am very new to hydro so please show me what I am missing. If your plant is "eating" nutes and water at the same rate wouldn't you want your add backs to be at the same EC as the bucket?

Click to expand...

If plants are eating nutes quicker than they're drinking water, the EC is going to go down. (Add stronger nutes back.)

If plants are drinking water quicker than they're eating nutes, the EC is going to go up. (Add diluted nutes back.)

If you've got your nutes at just the right level, EC should remain relatively stable as the water level goes down. (Add normal strength nutes back.)