Sampling rockwool with syringe - CRAZY results

[hazy]

No expert here so take it for what it is worth. But...pH dropping like that (kind of the opposite of what one would expect in Rockwool given its rep for raising pH) followed by rising ppms could be first a sign of dying roots (dropping pH) and then the plants not taking in the nutes due to the lack of healthy roots (rising ppms). Then that sort of becomes a spiral as ppm goes higher roots become more dehydrated, pH drops further...etc, etc.

It will be interesting to see if the same trend occurs in the winter when you do not have difficulties. Perhaps an enzyme product might help in the summer.

But...like I said do not take this as an absolute truth. It is just a thought.

What happens when pH drops too low is that the plant takes up excessive nutrients causing toxicities. High pH causes deficiencies. Although too much of some things cause restriction of others. For example low pH can cause aluminum to be taken up to the point where it restricts iron. Twisting leaves are a common sign of low pH in the medium. And of course due to ions that were disassociated, reassociating as the medium dries, they may form into bad stuff like sodium chloride or calcium carbonate. these cause stem weakness(brittleness) at the base, restriction of water uptake and salt toxicities.

So short of running lower ppms always, is there any other option besides a regular flushing?

I use coco, and have the same problem. I have been using a much lower nute concentrate and it works to keep the leaves from getting twisty, but some strains are telling me they want more I think.

 

[JackReddin]

So the question should be, Would top flushing the RW cubes work in ebb and flow?
Maybe once a week flush the top of the rockwool cubes or every 2 weeks depending on the readings you get from the cubes.
Has anyone tried this?

 

[ItsAllOver]

I just started doing this.
I did the first one at week 3, which was my first res change.
I think that's the plan, every res change. I did not, and cannot, sample my cubes, though, because I don't have the tools. I don't care though. It's looking good.
I just put a few gallons of water in a bucket, and ran a pump, using the hose to direct the pHed water...
I'll be doing waterings like this for my flush period, I think...

 

[sarek]

JackReddin... Thats exactly what you should do is to run solution over ebb n fow cubes, top feeding to do what we call rinsing. We have been doing rinses more often, every week minimum now. sometimes more. Either 1) resevoir solution pumped over cubes, or 2) use a cup to do a little at a time manually (tho i do not think this is as good) or 3) use hose water. All seem to be benificial.

One thing that might be bad is if u put H202 into resevoir and then put over cubes this sterile solution it can kill all the beneficials in the top of your cube. I believe that benefical bacteria live in top of cube as well so keeping the cube in good shape keeps these benies happy. If it gets really salty bacteria might die or weird non beneficial bacteria may start to grow.

Rinsing we call this process. Flushing is what we do last week or two, running cubes in water or something.

 

[californiajoe]

good information. thanks guys!

 

[Randybobandy]

All that must be done is to point a corner of the cube towards the ground. Catch the "runoff" into a container and measure. Threw the neddle away a long time ago.
Hey jack flushing from the top in ebb and flow is recomended. Nutrient salts tend to accumulate at the top of the medium with that system. But if you can get your flood height up there it would suffice.

I think the high readings are do to measuring at the top of the hugo. The higher up on the block the higher the ppm reading will be. BTW I love doing ebb and flow with hugos. If you know how to use rockwool it works sooo well. I really don't get why most growers don't like it.

 

[sarek]

Interesting observation. When rinsing cubes in healthy tray its all god. If on the other hand there is a sick plant, and you rinse with recirculted nutes that might be infected, you can infect other cubes. so if sick plants maybe use tap water to rinse.

Also be careful if you are drawing liquid from ill plants that you clean syringe before injecting into another plant! Rinse it in a bit of water between sick plants and healthy