Grow Mediums pH changes in DWC (Bubbler)

[ramone515]

Hello all,

I am trying to grow a Royal Queen Seeds Easy Bud in a PLANT!T Aeros which is actually a simple DWC "Bubbler system" with a 15L tank. I am using tap water, which I am passing throught a filter (like Brita) and let it sit for 24 hours, GHE Flora series, about 3/4 strength and I have a digital pH meter from ebay, buffer solutions and GHE pH down (not liquid, salt-like).

I am now in my 3rd week in the grow and I am having troubles setting my pH to a nice 5.5-6.5 range.

I changed the solution 2 days ago,

- old water pH was 6.6 (was around 6 when I started 2 weeks ago). I disposed all the old water.
- added fresh water, my nutes and found a pH of 7.2. I used pH down in small steps, mixing the tank thoroughly each time, until I had a pH of 5.7.
- placed everything back in place.
- a measured 6 hours later and the pH was at 6.3! As this seemed wrong, I measured again 6 hours later (12 hours in total) and the pH was 6.7!
- I put some more pH down that bought the pH back to 5.9.

All this brought some stress to my otherwise healthly plant:



The question is, how can I manage pH? Maybe I should get liquid pH down in order to know how many mLs are needed?

When should I measure pH to take the correct value and how can I do that without getting of range and damaging the plant?

Note that I am always calibrating my pH meter (even though most times the value is correct) before every measurement, especially because I have these problems.

 

[Grey Bear]

Ramone,
Keep this thread as a log for this grow.
Ask questions specific to it and I will try to advise as needed.
It will make it easier for all the afn staff to quickly get a sense of your grow when advising.
A few pics every few days generally gives a good visual along with your observations.
As for ph.
As long as it is within 5.2 -6.7, I do not worry at all.
If it goes below or above that for long and the nutes are fresh I will bump it back into range. If it keeps swinging out of range, you either need to change the rez or there is another problem if it is fresh.
Keep on going, she is not looking bad.

 

[TxOld Dude]

Ramone

I've found that GH Flora has buffers and resists ph changes. The best (for me) when making new solution was to pH first then add nutes afterwards. Add in stages, let set, measure, repeat. It'll settle down...

 

[pop22]

It could be your water, depending what minerals are in it, it can cause erratic ph. What is the ph of your water, right from the tap? a 7.2 after adding nutes may mean your water ph is very high as nutes almost always drive ph down. I use GH Maxigrow and Maxibloom, and it would take my water's ph from 7.2 to 4.3! That's why I set ph after adding my nutes now. Get some distilled or RO water and see how that works, should give you better ph control. If it does, you can always cut your tap water 50/50 with distilled/RO to save money and it will help. I just had water issues and by adding 50% distilled to some tap water, I discovered that my water was what was damaging my plants. Maybe getting your water tested would be a good I idea, especially if your drinking it...

 

[TxOld Dude]

Yeah, but he's using Flora not Maxi...

 

[pop22]

Yeah, but he's using Flora not Maxi...

Have you tried checking ph before and after? do you know if it affects ph and in what direction? Isn't the range of the buffers in the nutes limited in just how much it can affect the ph? Sure seems like a big ph change. Just asking and looking for info.

And the information provided still make me think the issue is his water.

Oh, I just checked and all GH nutes are buffered.

 

[pop22]

Here is some info from GH:

How important is water quality in hydroponics?

Answer: Water containing too much calcium and magnesium (called "total Hardness") may create serious problems. Contact your municipal water supplier who can provide you with an analysis of your water supply. If you are using well water, many laboratories can provide you with an analysis if you send them a sample. If the dissolved salts in your water supply measure 200 ppm or more, we strongly recommend that you obtain a water analysis to determine calcium content. Excessive calcium is the main factor in determining if your water is hard. If an analysis of your water supply reveals that the Calcium content of your water supply is greater than 70 ppm (mg/liter) you should use Hardwater FloraMicro. Hardwater FloraMicro provides rapidly growing plants with a combination of chelated micro nutrients uniquely formulated for hardwater conditions. Other options are to collect rainwater, install a reverse osmosis filtration system, or use purified water. Do not use mineral or "spring" water, which can unbalance the nutrient solution, or even be toxic to plants.

 

[TxOld Dude]

What's the ppm/ec and ph of the water straight out the tap?

 

[derek420colorado]

pH fluctuation is an ongoing problem and something that everyone who grows in DWC deals with to dome degree. I personally use the "swing" method(a term that I have made up) as stated above the range in DWC is from about 5.5 to 6.5 or so. I check my pH once sometimes twice a day and usually set it in the morning at 5.5 and by the next day it is usally around 6.1-6.3 and I then set it back down to 5.5. Here is a DWC pH chart that Steelyrat posted and it is really helpful. It just explains which different nutrients are abosrobed at the different pH levels. The only advice I would give is to become OCD about your pH, check it often and adjust accordingly when nessacary. Hope this helps, also if you have any other really specific questions Muddy is the MAN when it comes to things pH related

 

[ramone515]

Hey,

I didn't login back to the forum as I was pretty disappointed with the well being of my first DWC grow. Thanks for all the replies though.

First of all, the water in my area is good. A bit hard, but prefectly drinkable, with a pH of 7.0 to 7.2.

I got a new container to premix the nutes a day before, as it was suggested to me. After I've managed to keep my pH stable for several hours,

After I had the water set to 6.0 for about 12 hours in the other container, I changed the water in the Aeros with the fresh solution. Unfortunately in about 6 hours the pH was 7.8 !! I lowered it again to 5.8 but the next morning it was back to 7.6...

Long story short, I've also noticed extensive root rot, which happened in just 24 hours... Since then I change the water everyday and it always rises back to 7.0+ and I have to readjust 2-3 times a day. It also becomes muddy and smelly. I am certain it happens due the root rot. I tried some H2O2 and wait to see if it is a lost cause or if I can keep growing it.

I'll add pictures tomorrow.