Am I underfeeding?

[Surfer Joe]

I have a big, bushy auto northern lights growing in a 5 gal bubble bucket and it is in the early middle stages of flowering (I think) It was sprouted on dec 1.

I have been mixing up its nutes following the canna guide for aqua nutes for normal feeding, but at about 75% strength, using all of the products listed and also a bit of cal-mag.

When the buckets get changed, the nutes are about pH 5.6/1100ppm/EC1.9, and then it drops gradually over the next 4 days and stabilizes at about 550ppm/EC1.0. But with my water, the numbers are actually 260ppm/ec0.6 (My tap water is pH 7.4/EC 0.4/290ppm)

The pH ranges around 5.6-6.1 and I use water at about pH 5.7 to top up each day to just below the mesh pot.
I keep on just adding water to top up even after the nute readings bottom out for about 7-8 days before switching buckets with new nutes.

Am I feeding it enough?

I noticed that the plant was looking a little yellow, so should I switch the buckets and give it fresh nutes when it has sucked out the nutes?
Should I simply add fresh nutes to the old bucket periodically?

Should I aim to keep the nute levels constant by adding nutes and water each top up and then doing a bucket change every 8 to 10 days to deal with any buildup of unused nutes, etc.?

Here are a couple of pics. Thanks for any advice.

 

[4u2sm0ke]

Back whenI ran DWC I would run at full strength...if the plant is telling you it wants more(yellowing leafs) than bump up the Nutes....and I also just toppped mine off with fresh nutes..never changed the Buckets..The Hydro guru's will chime in shortly

:48:

 

[WeedHopper]

I fed mine until I got a little Turn and Burn,backed off a little,and they always did great. I changed my buckets out once every 7 to 10 days.

 

[Hushpuppy]

I wouldn't run the nutes any higher each time than 1400ppm which is a little bump up for you. But I would also top up with nuted water(at same 1200-1400ppm) like you said and still do bucket change every 10 days.

 

[Surfer Joe]

I have found that topping up with nutes doesn't work for me.
When I did top up with nutes, I lost control over the pH and it kept shooting down into the 4.5 range repeatedly.
I eventually solved it with replacing the bucket and going back to my cycle of starting a bucket at 5.8 and letting it rise to about 6.3 in the first two days, then adjusting it back to 5.8 and all the time just topping up with water at about 5.7.
When I do this, it stays stable for the rest of the time until I change the bucket again.
But I am wondering if I should change the buckets sooner?
If the ppms go down for the first 4 days and then stop decreasing, should I switch buckets then or keep topping up with water for a full 10 days before switching?

 

[The Hemp Goddess]

I would be dropping the water level. With bubble buckets, you only want to keep the water level at the bottom of the net pots until you have good root growth. As the roots start to grow, drop the water level so about 1/2 of the root growth is submerged. That is generally about 3 gallons of nute solution in a 5 gal bucket.

I also think that you should be letting your nute solution go from about 5.4 to about 6.0 rather than 5.7 to 6.3. With hydro, there are some nutrients that the plants are not going to uptake at levels of 5.7 or above. Also, I don't think that there are any nutes that need a 6.3 pH.

If the ppms are going down, I personally would up the ppm concentration on the nutes. I really like to push mine until I get a bit of nute burn on the tips of the leaves and then back off some.

Here is a link to a chart that shows nutrient uptake at different pH levels for both hydro and soil. http://www.marijuanapassion.com/forum/attachment.php?attachmentid=1833&d=1141100090

 

[Surfer Joe]

Thanks. The rootball has grown so big that it fills most of the bucket below the net pot, and I was concerned about leaving it exposed to air all the time in case it suffered.
I am going to try starting the nutes at about 5.4 and see how that goes and keep the water level lower.

 

[robertr]

If your tap water is 290ppm you have hard water, I don't know if that helps

 

[Surfer Joe]

Thanks. I know that we have hard water, but there's not much I can do about it.

 

[trillions of atoms]

You can get an ro unit....

try bumping up the feed till you get a little burn on the very tips of the big fans- you know your on the edge.

the ppms are dropping because tgey are eating well.

 

[orangesunshine]

bump them till they burn a bit---others might say since u are 1/2 way thru flower it be totally normal to be getting a bit yellow as ur plant dont want any more nitrogen as it winds down to harvest