Grow Mediums HELP! D39. My 5th growth in row is failing. (1st with autopots) Yellowing TOP leaves. PH, zinc,iron, something else?

[BII]

Well, Yes and No...... You have no way to know what was in that 500PPM coming out. Run-off is a poor indicator of what is actually happening in the pot although in hydro the information can be useful to determine trends. Roots of the plant will exude chemicals that change the PH of the root biome. It does this to tell the microbes to make more or less P-K available to the plant. Yes there is a microbe biome even in DWC. The microbes work overnight to make these ions so the plant can uptake them as soon as transpiration begins in the morning. This is why you do not want to start fertigation until after transpiration has started one or two hours after lights on. If you start fertigating too soon you wash these ions out of the root zone. In a well managed coco grow this is not as critical as in soil because theoretically our nutrient blend has these ions available anyhow, that said GroDan (Rock Wool) preaches never to fertigate prior to transpiration!

What comes out of the pot is not as critical as what goes in. If you PH properly going in the nutrients will be available to the plant.

I am always happy to add my to a grower asking questions. I don't have all of the answers and new science comes out every day. So read what others say, research, question everything and take it all into consideration then decide on a path forward After all you are the farmer!

While on the topic of feeding, I don't recall much advice at all about feed temperature.

Wiith regular drain-to-waste top feeding in coco/perlite (or other non-soil medium), what is the optimal temperature, both for the feed water and the coco/medium? For example, is it better for feed to be at room or in-tent (warmer) ambient temp. or cooler (water carries more gasses/O2)? What should be coco/media core temperature? When, if ever, should we try to adjust the medium's temperature using feed water?

 

[Mañ'O'Green]

While on the topic of feeding, I don't recall much advice at all about feed temperature.

Wiith regular drain-to-waste top feeding in coco/perlite (or other non-soil medium), what is the optimal temperature, both for the feed water and the coco/medium? For example, is it better for feed to be at room or in-tent (warmer) ambient temp. or cooler (water carries more gasses/O2)? What should be coco/media core temperature? When, if ever, should we try to adjust the medium's temperature using feed water?

Water/reservoir temperature is critical in DWC and 68°F is the target. This is the temperature that water holds the most dissolved oxygen. This is not a concern in Rock Wool or Coco because oxygen is carried to the roots in the dry back which is achieved every day/night. Of course you do not want to scald or freeze your roots Temperature was a driving factor in my move to rock wool from DWC. My tent can reach the mid 90s in the summer daytime here. I had DWC res temps as high as 85°F. If it were not for HydroGuard that crop would have been a 100% failure. I got a fair harvest but the quality was shit compared to what I grow now. Another important aspect was a huge saving in nutrient costs. Rock wool fertigation is much more economical.

 

[BII]

Water/reservoir temperature is critical in DWC and 68°F is the target. This is the temperature that water holds the most dissolved oxygen. This is not a concern in Rock Wool or Coco because oxygen is carried to the roots in the dry back which is achieved every day/night. Of course you do not want to scald or freeze your roots Temperature was a driving factor in my move to rock wool from DWC. My tent can reach the mid 90s in the summer daytime here. I had DWC res temps as high as 85°F. If it were not for HydroGuard that crop would have been a 100% failure. I got a fair harvest but the quality was shit compared to what I grow now. Another important aspect was a huge saving in nutrient costs. Rock wool fertigation is much more economical.

So for simple coco top feeding room temperature/68˚F water is best. That keeps things simple.

What about coco/medium temperature? For ex., I store my coco, perlite, etc. in an unheated area. It can get below freezing here in the Mid-Atlantic region. In the winter, I generally make up pots and let them sit inside (at room temp. or in the tent) for 2-3 days, or longer before transplanting (Rapid Rooter plugs or equivalent as soon as any stem or root pokes out, is visible). The surface coco/medium can be warm/normal, particularly from light if in the tent, but the core coco often still remains/feels cold, colder than pots long in the tent. This is from manually handling the coco - I haven't taken temp. readings.

In this type of context:
a) What are the minimal, optimal and maximal coco/medium core temperatures?
b) How long does it take for say a 5 gallon pot of coco/perlite sitting in a heated room or within the tent (warmer) to go from say 30s-40s˚F up to desired temperature?
c) When, if ever, should we manually adjust the temperature, such as feed warm(er) water to bring up the coco core temperature?

 

[logangrowgan2020]

Water/reservoir temperature is critical in DWC and 68°F is the target. This is the temperature that water holds the most dissolved oxygen. This is not a concern in Rock Wool or Coco because oxygen is carried to the roots in the dry back which is achieved every day/night. Of course you do not want to scald or freeze your roots Temperature was a driving factor in my move to rock wool from DWC. My tent can reach the mid 90s in the summer daytime here. I had DWC res temps as high as 85°F. If it were not for HydroGuard that crop would have been a 100% failure. I got a fair harvest but the quality was shit compared to what I grow now. Another important aspect was a huge saving in nutrient costs. Rock wool fertigation is much more economical.

Do you have a link to a thread that details your setup? I've been telling myself I'll do a DIY flood table or another rockwool setup for a while but just haven't pulled the trigger. Currently run DWC 5gals and have had mixed results.

 

[Mañ'O'Green]

So for simple coco top feeding room temperature/68˚F water is best. That keeps things simple.

I did not say that. It won't hurt but it is not necessary.

Yes, you want your growing medium in normal growing temperatures.

Do you have a link to a thread that details your setup? I've been telling myself I'll do a DIY flood table or another rockwool setup for a while but just haven't pulled the trigger. Currently run DWC 5gals and have had mixed results.

Take a look at my current thread: Ps. the link is in my signature.

SSSC - White Widow Creeps an Elephant

Super Sativa Seed Club Auto White Widow, Auto Creeper and Auto Elephant. I will be experimenting with an 8/4 8/4 light schedule to see if this speeds maturity time? If I don't like the looks of it as I go I will be reverting to 18/6. I have wanted to test this for a while. The first order...

www.autoflower.org

 

[BipolarBear91]

@Rasterman @St. Tom @BII @Hotfire @Cannaficionado - thanks to you all I had my first decent harvest!! I apologize for not updating faster, had a lot of personal life stuff to deal with


And of course, @Mañ'O'Green - thanks for looking at my water report and giving so much specific advice

I have only 1 low quality screenshot from 2-3 weeks from harvest. In the end I harvested at 90% milky,10% amber.

Quality is good (not the best I had , I guess the flowering stress did some damage) and I am very satisfied. Very, very satisfied

I wont talk about the weight - it was massive! I am/will be experimenting with cooking etc!
Thanks again, everybody!

 

[Mañ'O'Green]

Enjoy the fruits of your labor. Your quality will increase with your experience. Farming is a life long learning adventure!

 

[Rasterman]

@Rasterman @St. Tom @BII @Hotfire @Cannaficionado - thanks to you all I had my first decent harvest!! I apologize for not updating faster, had a lot of personal life stuff to deal with


And of course, @Mañ'O'Green - thanks for looking at my water report and giving so much specific advice

I have only 1 low quality screenshot from 2-3 weeks from harvest. In the end I harvested at 90% milky,10% amber.

Quality is good (not the best I had , I guess the flowering stress did some damage) and I am very satisfied. Very, very satisfied

I wont talk about the weight - it was massive! I am/will be experimenting with cooking etc!
Thanks again, everybody!

What strain is that? Very impressive how those buds stacked.

 

[BipolarBear91]

What strain is that? Very impressive how those buds stacked.

It is SODK by Mephisto.

Yes, it is huge. (I actually wanted to cut large middle portions off due to 65-70 % humidity. But figured it would be to much stress 3 weeks before harvest and I also had 2 good oscillating fans. Luckily, no botyritis)

Larfy/popcorny (it is a sativa though), but I could care less. My weight guess would be 6-8 ozs. It was a 15 litre pot, 100% coco.


This amount made me realize I dont need that much (for smoking). So now I am experimenting with edibles etc.

A nice side hobby which would be much harder to get into without this community

 

[BipolarBear91]

Enjoy the fruits of your labor. Your quality will increase with your experience. Farming is a life long learning adventure!

Hehe, just preparing for the inevitable societal (agricultural) collapse one joint at a time.
Now its time to learn to grow some potatoes (and put em in a stew)