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Background E.C

Morning all a quick question regarding ec I got a bluelab truncheon yesterday and tested my tap water it’s coming out at 0.7/0.8 now with it being so high when I start my dwc which will be in a oxypot Xl so 70litre res what should I be aiming for as a start point. My understanding is to stay on the lower end of the scale when it comes to feeding in dwc. I’m using AN Sensi Grow A+B and will be addingn some voodoo juice as I’ve read some good things about it. So Do I only mix feed in and make it up to say 0.9 which is only 0.1 of added grow or go upto 1.0 which still doesn’t seem a lot at only 0.2 of food. 

Cheers in advance 

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This is a topic I've had some issues with in RDWC. Clearly your hard water area like myself, and the trouble is with water like that it leaves you very little space to actually add plant specific nutrients / elements to the water without taking the EC over the normal levels. 


What I found is that to bring you EC up to a level where there is a good amount of phosphorous in the water for bloom you hit levels that will burn the shit out of the crop with the other Macro nutrients, mainly Nitrogen I'd guess, especially in bloom.


In the end it comes down to either trial and error of finding a perfect balance, or like me you may need to consider a decent RO system. Some may say RO is over kill but without filtering the water you have wasted 0.6-0.8 of your EC range on shitty tap water elements that the plants cant absorb efficiently. Once removed you can then use soft water Cannabis nutrients and your 1.1-1.3 bloom EC will now be purely plant based nutrients / elements.


My advice now to anyone with this issue is filter your water with an RO system, its the best buy I have made since getting the RDWC. You have to learn the levels again but once you do the plants really do show appreciation. 



e2a: just to add for anyone considering buying a filter, it HAS to be RO. Basic water filters dont lower the EC enough. Tried this and although it went down it was only 0.1ec, at best, so save the money and go straight for RO system, piece of piss to fit as well.




Edited by GreenVision
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Am in very hard water also and agree that it seems to be contaminated with piss (N) but also wondered if it might be a type of chlorine that doesn’t evaporate causing some issues? I was put off by the ro after seeing that plants can suffer a chlorine def when using it but better than an N toxicity during flower and not so much guess work if starting from scratch.. something to look out for if you switch to ro though as  a chorine deficiency looks a lot like a chlorine toxicity.. in coco I can take it to 1.3 without issue but starting at .75 it doesn’t leave much room so I compensate with more frequent feeds during bud.. I guess in Dwc you could do more frequent res changes but i have no experience with it to speak from.. as you say, ro is probably the way forward in our situation :smokin:

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@Era Well first off the crop needs a VERY small amount of Chlorine, and quite a few of the nutrients we buy now for hydroponics specifically can have it in as people are starting to use RO water more an more.


But if you feel an RO system is filtering all the chlorine from the water (which would be impressive) then you can just add some unfiltered water to your res before mixing your base nutrients.


As it stands I've not seen a problem yet, and the positives of filtering water for hydroponics for me far outweigh a possible Chlorine def, even more so for hard water areas, and Chlorine def is something that can be sorted by adding maybe 10% unfiltered tap water.


I'm sure you have read that def's in hydro come on quick, but they fix fast as well so I just watch close and touch wood as of yet not noticed anything close to chlorine issues. 

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Thanks for the info didn’t really wanna go down the R.O. route guess I’ll have to see how it goes with the feeding then gonna get a chiller today to keep res temps spot on as my room sits at 21 with lights off. 

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