DWC Add Back Question

[senate]

If you have a single tub DWC, and you are doing an add back method to keep a constant PPM instead of draining and refilling a res every week, how do you add the nutes exactly?

After calculating the correct amount of nutes, do you just add that to whatever amount of water needs to be added back to the res and pour in?

If there's ever a situation where the water level doesnt need to be raised, can you add nutes directly into the tub?

Thanks

 

[K11NG]

I would drain the rez at least once every 10 days, imo, but if you choose not to I would set accurate measurments on your tub so you know the amount of water you have in your rez at all times.
that being said once the ladies start to eat you will be adding water constantly. what I wouls suggest is fill rez and nutes, once the ladies start to eat then you will add water one day and the next nutes.
for example monday starts new rez 20 gals, tuesday you need to top off. your girls drank 5 gals so you add 5 gals. wednsday you notice the girls ate 10 gals, so you add 10 gals water but only 50% nutes called for the 10 gals. thurs add water as needed, friday half nutes of water added and so on so fourth. but like I said in the beggining I would really change rez out at least every 10 days or 2 weeks tops. its much easier to keep a hold of your ppms when you change out your rez weekly. hope this helps good luck

 

[senate]

Im still a little confused. Lets just make #s up here. Lets say my target PPM is 1000. The plants have drank some water and ate some food. Lets say I need to add X gallons to a 20 gallon tub to get it up to the right level again. From the add back equation floating around out there, I see I need to add 50ml of nutes back in the mix to bring the PPM back up to 1000. Do I just mix the 50 ml of nutes in the X amount of gallons Im adding back to the tub and then pour it all in at once? Whether X gallons stood for 1 gallon of 5 gallons, I would still add the 50 ml of nutes to whatever amount it was, and then pour into the DWC tub? Sorry - I hope Im being as clear as possible here.

Thanks in advance

 

[senate]

To add to the post above....

OR... Do you add the water back to the tub first to get your desired water level, and then add the nutes and stir?

Or does it even matter?

 

[devilbutt]

just change nutients every 7 to 10 days and save yourself alot of trouble. just add enough water to keep things working properly and adjust you ph accordingly

 

[senate]

Changing the whole res takes a lot more water than just adding back. I would think adding back would be easier with some basic math skills. I would love an answer to the question above if anyone knows. Thanks.

 

[ttystikk]

Changing the whole res takes a lot more water than just adding back. I would think adding back would be easier with some basic math skills. I would love an answer to the question above if anyone knows. Thanks.

The problem is that 'it depends'. It depends on how much your girls are actually eating, which itself depends on factors like temperature, light intensity and relative humidity. If I were you, and to some extent I am since I run RDWC, I'd just run water in the top off reservoir, and add nutrients directly into your DWC on an as needed basis. You're going to want to check your PPMs and pH daily anyway, just do it then.

And yes, change out your water every 2 weeks or even more often. This is a step that really cuts down on problems with nutrient depletion, lockouts, and opportunistic pathogens.

 

[John Ditchweed]

Just add the water back to the rez first( refill to desired water leverl) and then directly put nutes in rez till you re-rereach your desired ppm.... why mix a solution the add it to the rez and risk it being to much or little.... add water then nutes to ppm desired and then ph no guess work or much math to it.

 

[fuzzy]

1-2 gallon jug

In the diy UC.I add back water to disired level, then i take a gallon of 5.8 phed water, mix nutes and add to the epicenter till i get the ppms i want.May not be the correct way, but its worked fine for 4 runs now. peace,fuzzy

 

[senate]

John and Fuzzy - Exactly what I was lookin for. Thanks!

 

[Jalisco Kid]

I would replace the nutes once you have replaced 50% of the rez. I would only top off at 50% of nute strength. Otherwise you could be gaking up your feed by keeping salts it does not want to eat to high.
If it was a rcdwc I would replace nutes once you are around 80%.

 

[senate]

Thanks JK.

 

[K11NG]

Just add the water back to the rez first( refill to desired water leverl) and then directly put nutes in rez till you re-rereach your desired ppm.... why mix a solution the add it to the rez and risk it being to much or little.... add water then nutes to ppm desired and then ph no guess work or much math to it.

that sounds easy but your looking for problems. i use house and garden the whole line. how would you know how much of all the additives to use if you just go by ppm. u need to know how much water your adding to know how much nutes your adding unless your just running an a and b mix, then just add both evenly till desired ppm.