Relative Humidity

[crisscross]

I am running a simple bucket dwc. This is my first time growing indoors and I have some general questions that I am hoping an experienced grower can help me with:

1. What RH is ideal? I have a climate controlled area and live in the southwest United States so the air is exceptionally dry. The RH outside is about 30% so with my a/c running it can drop to 20% indoors. Is that too low of RH and should I increase it and if so to what % approximately?

2. I start my bucket every week at 5.2 ph. Gradually the ph climbs to as high as 5.9/6.0 before I lower the level with ph down. I understand that an increasing ph is not uncommon but after doing some research I have found that plants absorb different nutrients at different ph levels. Should I let my plant stay at 5.9 or constantly push it back down to 5.3/5.4?

3. I think I understand the use of a TDS meter in order to confirm initial water purity and to confirm the level of nutes in the water. My question is, I do a res change once a week--by the end of the week, should the tds levels change?

4. During veg is it okay to trim lower fan leaves when they are dying off/about to be replaced by new leaves or is it better to let them fall off naturally? I just don't like messes is all.

Thank you for your input!

 

[Bunz]

1. During flower most of us would kill to get RH down to 30%, however ideal is 34-45%. During veg you should shoot for 60-70%

2. Not a hydro pro (I do soil myself), but after years and years of reading, the growers I trust start their PH off low and allow it to climb before doing a res change. It allows the plants to go thru the entire range absorbing all the nutrients.

3.Unless you've topped off your res, your TDS should rise as your nute solution lowers either by plant usage or evaporation. This is why most recommend topping off with plain water or 1/2 strength nutes.

4. If the leaves are drying, it is fine to help out mother nature and trim them off yourself. You will not do any damage to your ladies doing this.

HTH

Bunz

 

[spadedNfaded]

I ph my "top-offs" lower, at 5.5, and my refills at 5.6. I always allow my plants to sway with pH as it give them a better spectrum of availability. Also, it's just natural as the plants use water and nutes for the pH to sway a bit.

You could check your TDS at the end of the week to see what your plant is using during the week. That should give you a good idea of what strength to top off.

Leaves that have lost their green are doomed. The plant is using some stored nutrients in the leaves. I wouldn't take them off until they contain no more green as if the plant is still "searching" for nutrients to make up the difference it will go to the next leaf and start the process over again. Its best to leave it there until it's be depleted and let the plant eat it as long as possible before going to another one.

- SubN

 

[FreezerBoy]

Constant pH guarantees unbalanced feeding and can lead to toxicity, deficiencies or both. You want pH to swing.

pH movement is only 1/2 the measurement. You need to combine it with EC movement as well. EC up, pH down is too rich. EC down, pH up is too lean. The key is to feed in the direction of pH movement (providing EC has gone in the opposite direction as it should) While I can't say for sure due to insufficient info, pH climbing is quite possibly a request for more food.

Personally, I force pH to drop by barely over feeding. This causes EC to climb and pH to drop and, after 2 weeks, topping off with straight tap water lowers EC and raises pH back to my starting numbers. I'll keep this up for weeks to months until I see signs of unhappiness (usually a slight yellowing of the leaves) at with time I'll flush the res. I've done 20+ week grows with only a couple of res changes. However, I grow 1 plant in a huge tub. Several plants in a small tub probably works differently.

 

[SeaMaiden]

I am running a simple bucket dwc. This is my first time growing indoors and I have some general questions that I am hoping an experienced grower can help me with:

1. What RH is ideal? I have a climate controlled area and live in the southwest United States so the air is exceptionally dry. The RH outside is about 30% so with my a/c running it can drop to 20% indoors. Is that too low of RH and should I increase it and if so to what % approximately?

2. I start my bucket every week at 5.2 ph. Gradually the ph climbs to as high as 5.9/6.0 before I lower the level with ph down. I understand that an increasing ph is not uncommon but after doing some research I have found that plants absorb different nutrients at different ph levels. Should I let my plant stay at 5.9 or constantly push it back down to 5.3/5.4?

3. I think I understand the use of a TDS meter in order to confirm initial water purity and to confirm the level of nutes in the water. My question is, I do a res change once a week--by the end of the week, should the tds levels change?

4. During veg is it okay to trim lower fan leaves when they are dying off/about to be replaced by new leaves or is it better to let them fall off naturally? I just don't like messes is all.

Thank you for your input!

I can answer questions 1 and 4, would like to comment on Q3.

First, what's "best" can have a lot to do with the total conditions, as what the best RH is also depends on temperatures. I have found that, for my indoor girls, generally, going with temperatures in the 76F-80F range (difficult for me, I only grow indoors in winter and it's a basement) the plants respond best and show best growth and best turgor when RH is between 65%-75%. They actually resond the very best at an RH of 80%+, but it scares the living shit outta me so I'll leave the door open if it gets that high (plus, my glasses fog up something fierce). The only time I've ever had an issue with any type of mold showing up was my last coco run and they had been infected with root aphids. I did not Dx the root aphid infestation until the known rock-solid genetics all hermied on me, that was the clincher (along with some other stuff, too much to list here, off topic).

I found a great little vapor pressure deficit calculator that helped me grok the why of it. Remember also please that I tend to go with what the organism is telling me over anything else, but I do like to keep logs of numbers, etc. Just read the information provided here, I found it easiest to wrap my head around.
http://www.hydro.co.nz/1_information/1_vpd/info_vpd.html

Q4: I've always removed dead or dying growth, with the thinking that after it's done its job, it is not only going to fall off anyway, but in that condition can provide an invitation for disease to set in. I feel that once it's done its job it also does little more than take up space and resources. I have found that damn near all plants that I grow respond better to a little judicious pruning (not my Camellia, though, and now I know that they need to be treated differently).

Q3: It's extremely important to understand not only what a TDS meter does, but how. It is a conversion of electrical conductivity (aka EC, as most often measured in microSeimens), as is ppm. As such a measure, that means that it can only measure those molecules or compounds that are indeed conductive. What does that mean in the grander scheme of things, anyway? It means that if you're also incorporating organic molecules into the mix, you cannot generate anything resembling an accurate measure of their density using TDS (EC). You can measure chemical salts and some, if not most, dissolved minerals, but you cannot accurately measure, for instance, what's in that worm casting or alfalfa tea, or the 'density' of the tea.

Assuming you're using chemical salt nutrients (and by your growing method I'm going to guess that you are, but won't assume that far), then your method of using the TDS meter to gauge density, uptake, etcetera, will serve you well.

Oh yeah, let the pH drift. Maybe even out of range once in a while.

 

[crisscross]

Thanks for the replies everyone. I am still confused on question #2.

My ph is started at 5.2 when I do a res change. By the next day the ph is 5.7 or so. If I leave that alone by the following day the ph is 5.9--a tad high imo. Therefore, should I lower the ph to 5.2 again on day 3 and let the ph climb again on its own or should I just leave the plant alone?

 

[SeaMaiden]

Does the plant look stressed when the pH drifts? Both FreezerBoy and I suggest allowing it to drift.

 

[crisscross]

SeaMaiden and FreezerBoy--I get the point of allowing the ph to drift and the benefits of allowing the ph to drift. I guess I haven't been clear in my questioning. What I want to know is what would you do in the following scenario:

start at ph 5.2
24 hours later ph is 5.7
24 hours later ph is 5.9
8 hours later ph is 6.0-----at this point the ph seems to be a little high, yes? so, I have allowed ph to drift for 2.3 days at this point. Should I lower the ph back to 5.2 and allow the ph to drift back up to 6 (or potentially higher) OR should I leave it alone?

plant looks great for its age (4 weeks from seed) and is only being fed 15% of maxibloom because during week 2 I overfed and burned her a little.

 

[FreezerBoy]

Thanks for the replies everyone. I am still confused on question #2.

My ph is started at 5.2 when I do a res change. By the next day the ph is 5.7 or so. If I leave that alone by the following day the ph is 5.9--a tad high imo. Therefore, should I lower the ph to 5.2 again on day 3 and let the ph climb again on its own or should I just leave the plant alone?

Once again

pH movement is only 1/2 the measurement. You need to combine it with EC movement as well.

We can't help if you hide essential info. When you go to your mechanic, you don't say "My car." That doesn't say anything. You say my car IS: broken, slow, smoking, grinding...

How big are the plants? How old? Check your journal and post daily EC and pH movement for the last week. Until we have BOTH EC and pH we can only guess.

 

[stonedar]

what do you do as far as add backs. you are doing a small single res dwc, that you routinely change the water in once a week.
my question is do you add any water or a weak water/nute mix back into your res DURING the week?
some water will evaporate so unless you add something your solution should get stronger as the week goes on. the plant uses water & water evaporates faster than the plant uses nutes. normally, that is.

so during the week on say day 4, the midway point, you can add back say a 25% nute solution. or you can add back straight water. it doesn't seem to matter people do it both ways.

this add back water can be ph'd to 5.0 to bring your solution back to an acceptable range

 

[crisscross]

I have been doing small 'add backs' of straight water. Now I will add nutes and ph lower. Thank you so much stonedar for the help!