Grow Mediums DWC: As plant drinks, replace with only water? Or, water + nutrients?

[PhilGarcia]

Hello! General advice states that you should replace the water & nutes in a DWC bucket once per week.

That is simple enough...but...as a plant drinks the water from the DWC bucket throughout the week, do you replace the water with clean/pure water? Or, water with nutrients in it? Or, do you not replace any water at all, and only re-fill once per week?

If you replace the consumed volume of water with nutes, do you do the necessary math to determine the amount of nutes for that volume? e.g, 1 gallon needs to be replaced, so you measure & use a 1-gallon quantity of nutes?

Thanks in advance!

 

[mclovin478910]

:group:Its a good idea to just top off with plain ph'd water unless your plants are thirsty for nutes possibly during flower. but if yours are young or you dont think they can handle the amount then just top with the plain h2o. Personally I would always top off with ph'd do be safe and keep stress levels low for both you and your ladies

 

[PhilGarcia]

McLovin, thank you kindly for your answer! Not having to do nute-math sounds nice!

 

[DWCocha]

Hi mate.Once my Blue mammoth started drinking so much that i was adding back a lot (1/2L a day?) I made a top up bucket with the same nutes as the res .... If the res is good then you want to add back with the same.I add water PH5.8 if the res is to strong to lower EC

 

[Greenink]

Hi, I am by no means an expert by I used the Lucas formula for my first grow and really didn't have any problems. It uses GH nutrients, only the Micro and the Bloom. Basically the idea is that you want to top off with nutrient solution any time your reservoir gets low. I found an addback calculator on another site that tells me exactly how much nutrients to add based upon the amount of water you are adding, the current PPM of water in the reservoir and your target PPM. Initially I consulted the calculator everyday, but after awhile I got a pretty good feel for it and stopped using it.

Fill your reservoir to whatever PPM you decide upon and run them for a couple of days. After the reservoir has dropped by a gallon (I have 2 gallon waterfarms) measure the ppm. If the PPM has raised, the initial nute strength was too strong, and you will need to addback a lower ppm mixture. If the PPM has lowered, you will want to addback a stronger mixture. After awhile, you will find that you are topping off your DWC everyday with nutrient solution and the PPM remains constant to whatever you decide. I ran my plants at 1000 (.5) ppm pretty consistently with good results. It also allows you to easily control the pH as you can adjust it daily, and you have a general idea of what to add (up or down) because you are adding back a solution with a lot of buffers so it is stable. If you are running strictly DWC with no topfeed, you need to top it off frequently so the roots are always in the solution.

If you do the Lucas formula, you will never completely change out your reservoir, start of flower to finish. Many people diasagree with this because if they are feeding on one nutrient more than the other, you will be left with a great abundance of one nutrient and totally f*** your plants up. This is why you want to use the recommended N-P-K ratios (I don't know them off the top of my head). I agree with this thought but I think the reality is that bloom start to finish is so short that this never becomes a real problem. i am sure that if you ran a plant for a year in a DWC you would absolutely have a problem down the road. The only drawback that I have found with all of this is that you are never really able to give your hydro stuff a good cleaning, so if you have a topfeed dripring like i do, it becomes clogged with nutrient salt buildup.

 

[Tavosvo]

Smaller res and bigger plant needs refills more often. Ill mix a fresh res at 1200, and by the next day it drank a bunch but ppm is 1400, so I do about a 3/4-1 gallon plain RO top off. Puts ppm back at 1200. Next day drank a bunch but ppm only up to 1300 or so. Do 3/4-1 gallon add back and ppm ends up a 1150. And so on. Ill do that till I'm at 1000, prob 3 days from res change, and then maybe ill add a little extra calmag and hydroplex to bring the ppms back up. Watch out though hydroplex really drops pH. I used to have gradually rising pH when I used tap water and no calmag. Now pH is basically always 5.8.

I like plain RO top offs on a slightly strong initial nute mix. I don't think plants take up all nutrients equally so it'd hard to know how much of each NPK they want. It's very simple and my lady gets to taste a stronger nute mix for a little while each day.

 

[MrMcbud]

the best advice i can give is what was given to me by Jtang,it has worked amazingly well.
i was away for 2 weeks and my complete noob fiance' grew a beautiful plant in my absence.

So the idea is.. You want everything to be stable.. Ok.. EC & pH most importantly..

Ok here's the scenario that I normally go through..

First off... I'm explaining as if my girl is in flower ok..

So I make a fresh res up with my 3 part feed.. Now I want to mix into the fresh bubbled water of my res the nutrient with the most calcium in it first.. So check your bottles for %'s of cal.. So with my nutes it's the Grow part has the most then the Bloom has some as well but less.. & the Micro has none.
So in goes my G part first.. Give it a mix up... Then the B part... Give it a mix then the M part.. Let mix & dissolve for a wee while then I pH the res to 5.8-5.9 (in flower) now I ideally don't want that pH to change at all.. & it will float around those figures if all is ok..

Now I've made up the res to say 2.0EC.. Set the plant in & away she goes.. Now by this time in my girls lifespan she has a massive rootball & she can drink.. Up to 4-5L per day or even more..
So I go the next morning to check my EC/pH now the water level has dropped & her EC is up to 2.3-2.4 (she is drinking more than she is eating) now I normally have 2 full buckets sitting bubbling.. 1 with plain water not adjusted at all.. & 1 with 1/2 strength nutes... The same ratios as my proper res jus at 1/2 strength.. Ok..

Now depending how much the water has dropped & how much the EC has risen determines wether I replace/add back with plain water or the 1/2 strength mix.. Like if its only dropped a little but the EC is away up I'd just replace with plain water.. Add back the same amount that has been drank & it hopefully will back at the 2.0 EC were you started.. & of course if the water level is away down but the EC is only up a little then I'd replace with the half strength mix.. Make sure this mix is pH'd.. Ok if your water level is down & your EC is stable or down a little then make a fresh res up & raise the EC by .2. The idea is that after you've added back to the res then your EC & pH will be where you set it at in the first place.. Everything stable.. As you know you can also judge it by how the pH is reacting..

That's the main fist of it bro..

Another thing keep your water level about 1" above the base of your net pot.. This promotes feeder roots & not air roots.. More feeders more uptake.. Check this regularly & keep it topped up & you probably won't have too many fluctuations in the res..

Plenty of air in your root zone as well McBud... As much as you can blow through it.. 20L per min minimum.. I've 60L through mine per minute.

I hope this helps dude.. & I'm only putting this out there.. You couldn't be leaving at a worse time dude..

Oh & make sure your pH is... In veg 5.6-5.7 & in flower 5.8-5.9.. Don't let it swing at all from those figures.. Period.

 

[PhilGarcia]

Excellent information, everyone! Thank you very much! All newbs thank you...