pH rising in Run To Waste supply RESERVOIR, WHY? How to Stabillize?

I have just started a Run To Waste feed system in Coco/Perlite, 2 1/2 weeks into vege and I noticed slow growth and the start of a nutrient deficiency I though to be Calcium so went to to store to get CaMg. I showed my local hydro store a leaf and he said it’s more than that.
I took a sample of my water in to get checked. The E.C was great but the pH that I had set at 5.8 was now 6.5 6 days later (My bad, amateur mistake. 3rd refill and I didn’t monitor it at all after setting E.C and pH each fill, I thought I didn’t need too, I thought once it’s set, it’s set, the benifit of a RTW system!!)
The first thing I did was replace my $25 ebay pH pen with a $120 one from my
I got home and did a side by side and both pH pens showed the same pH, so that wasn’t the problem. (even doing old school pH drops for a 3rd eyeball guest-imate!). Another $120 down (p.s I’m running 4 plants in a 4x4 tent, so I’m not a money maker, so $120 is a big deal when I didn’t need to spend it!!, Guess now I have a cheap spare!!)
Yesterday I washed and refilled reservoir with
30l water.

Reiziger Grow A+B 3ml/l. (Just looked at the bottle, too many ingredients to list!!)
Cyco Uptake 1ml/l (1% Humic acids)
Cyco B1 Boost 1ml/l (0.6%Nitrate Nitrogen, 1.4% Urea Nitrogen, 1% Phosphate P2O2, 4% Potash K2O, 0.25% Vitamin B1)
Cyco Dr Repair 1ml/l (3% water soluble Nitrogen, 0.6% Chelated Iron)
Cyco Silica 2ml/l (3%K2O Potash, 3% Monosillicic Acid.
I added pH Down and got it to 5.8, yet less than 24 hours later before feeding I checked and it had crept up to 6.1, which I promptly fixed before their feeding.
Is this normal for the pH to be so unstable in this circumstance?
I was under the impression with an automated Run to Waste system I could set E.C and pH and walk away for about a week or so, which I’m about to do for 10 days, leaving my house sitter with no experience to refill reservoir with easy instructions, I didn’t think they’d have to monitor the pH daily :open_mouth: .
Is it caused by one of my additives?? I know I’m using more additives than needed but I’m using the last of the Cyco brand before simplifying life and moving to Reiziger or Canna. I want to add Great White and have been told that enzymes and bacteria etc can play with pH even more, I’m ok with that, just not before my holiday!
Note, I adjusted my pH this morning at 8am to 5.7, Just checked at 2:30pm and it’s gone up to 6.7, only difference is the high air flow in. Could too much air in the water adjust the pH???
Any advice appreciated.

@JayMan I’m no pro but I think ph perfect would help you out. I’ve been growing in soil for a year and just started a coco grow, myself I feed or water every day at 1/2 strength to eliminate Ph fluctuations and it seems to make a world of difference . I use Fox Farm coco loco in smart pots so basically water to waste. Hope this helps.

Thanks mate, I’m going to investigate that as I head to my local soon. If you are using run to waste why the half strength? is that your nutrient level? This is only my 3rd grow. I started in a soil mix for first grow, 2nd was in Coco/Perlite and hand watered with nutrient mix made as needed, now I have smart pots and automated water than runs to a waste bucket and not recycled, which I know with a recirculating system does need pH attention, which is what I was trying to avoid!! Don’t get me wrong I’m not lazy just blody confused!!
I think I’m going to get half a dozen buckets and make different mixes to see if I can Identify my problem.

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Over time ph is going to rise with out Ph perfect.
As for why feeding so much… I saw few videos on u tube about 1/2-1/4 strength every day to get a better quality bud . Will that work that way I don’t know. I do know I don’t have problems with Ph or nute burn and my girls look amazing in my eyes but there my girls so I’m biased I guess.

Do you have an air stone in the res? That would help I’m sure.

Not my cup of tea :coffee:️ yet let’s get some people on here to help you out @Donaldj @Aquaponic_Dumme @garrigan62

Drain to waste is basically hand water with the exception being it is auto and on a timer the fact it isn’t remaining stable in res could be due to temp changes lack of o2 and or crappy nutrients :wink: Is this an ornagic product line or a sterile chemical nutrient line like GH flora series? Ph stablity is based on ppm nutrient interaction and nutrient circulation (products settle) and ph changes an airstone or circ pump helps keep nutrients mixed. What is your source of water tapwater loses chlorine and gasses which changes it’s ph as well

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Hope this helps

“pH And Hydroponic Marijuana”

When growing hydroponic marijuana the pH of the nutrient solution should be between 5.5 and 6.8. In most cases optimal pH is about 5.8 to 6.3 but this may vary slightly depending on the particular marijuana strain and the growing conditions you provide.

Some growers report good results with pH as low as 5.0. You can experiment to see what works best for your particular plants but always keep the pH between 5.0 and 7.0.

Measure the pH right after you add the nutrient solution to the reservoir (mix well first) because the nutrients will change the pH level of the water. Check the pH level about once a week.

                                                                                                                                               "Adjusting pH of Hydroponic Setup"

pH-up and pH-down solutions are used to adjust the pH level of hydroponic nutrient solution and hydroponic media when the pH is out of range. pH-up (also called pH increase) is used to raise the pH level and pH-down (also called pH decrease) is used to reduce the pH level. A pH-up or pH-down solution for hydroponic or aquarium use is recommended.

For hydroponic applications, nitric, phosphoric or citric acids (even vinegar) can be used to lower pH, while potassium hydroxide can be used to raise pH. If you understand what you are doing, you can use them instead of buying pH-up and pH-down solutions (contributed by james and jorge).

However, if you aren’t sure of the correct amount of acid or base that is needed to adjust the pH to optimum values, it is best to buy a solution specifically made to raise or lower the pH and carefully follow the manufacturers instructions.

Unless directed to do so by the manufacturer, don’t try to adjust your pH by more than 0.2 per day. Make drastic changes over a number of days. If your pH is 7.0 and you would like it at 6.5, try lowering it by 0.1 a day for 5 days (or do it even more gradually). Overcompensating can spell disaster for your garden.

                                                                                                                                            "pH And Marijuana Growing In Soil"

When growing marijuana in soil the pH of the soil should be between 6.5 and 7.0. When growing in containers, a single pH reading for each container is recommended. When growing outdoors in a garden, it is best to take two or three pH measurements from different areas of the garden.

If you have a large garden, you may have to adjust the pH in various parts of your garden to different levels. Check the pH once every one-two weeks.

Unlike hydroponics where the nutrient solution is in a single reservoir and only needs to be checked once, a soil garden will get its nutrients from the soil it is growing in. Even a small garden that contains a few plants may have soil that varies in pH from one area to another.

Most fertilizers cause a pH change in the soil. Adding fertilizer to the soil almost always results in a more acidic (lower) pH. As time goes on, the amount of salts produced by the breakdown of fertilizers in the soil causes the soil to become increasingly acidic and eventually the concentration of these salts in the soil will stunt the plant and cause browning out of the foliage.

Also, as the plant gets older its roots become less effective in bringing food to the leaves. To avoid the accumulation of these salts in your soil and to ensure that your plant is getting all of the food it needs, you can begin leaf feeding your plant at the age of about 1.5 months.

Dissolve the fertilizer in water (worm castings mixed with water will work well for leaf feeding) and spray the mixture directly onto the foliage. The leaves absorb the fertilizer into their veins. If you want to continue to put fertilizer into the soil as well as leaf feeding, be sure not to overdose your plants.

                                                                                                                                      "Adjusting pH of Marijuana Grown In Soil"

A good way to stabilize soil is to use dolomite lime (calcium-magnesium carbonate). Dolomitic lime acts slowly and continuously, so soil will remain pH stable for a few months.

Using fine size dolomite lime is important, coarser grades can take a year or longer to work. You can find fine size dolomite lime at any well stocked garden supply center.

Dolomite lime has been used by gardeners as a pH stabilizer for many years. It has a pH that is neutral (7.0). When added to soil in the correct proportions, it will stabilize soil at a pH near 7.0.

When growing in containers, add one cup of fine dolomite lime to each cubic foot of soil. Mix the dry soil thoroughly with the dolomite lime, then lightly water it. After watering, re-mix it and wait for a day or two before checking the pH. When growing in an outdoor garden, follow the dolomite lime manufacturers instructions.

Lowering soil pH: small amounts of composted leaves, cottonseed meal, or peat moss will lower the pH of soil.

Raising soil pH: small amounts of hardwood ashes or crushed oyster/egg shells will help to raise the soil pH. Hydrated lime can also be used to raise the pH of soil. In containers, use no more than 1/8 cup of hydrated lime per cubic foot of soil (per application). Mix it into warm water, then apply the water to the soil. When growing in an outdoor garden, follow the manufacturers instructions.

Wait at least a day or two before checking the pH level of soil after attempting to raise, lower or stabilize it. If adjustments still have to be made, use small amounts of whatever material you are using. Don’t try to adjust the pH more than 0.1 every two days.


Yes, I actually have a large dual outlet air pump with 2 large air stones in a 50l res with 40l water (some may say overkill!!). I was wondering whether too much air could cause a problem or affecting my pH.
Cheers bro.

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Temp stays stable around 23.5- 24’c (Temp controlled room)
o2 is plentiful and placed for water movement (I was wondering whether too much air could be an issue
Not organic nutes. Just started Reiziger Grow over Cyco Grow nutes. (I think my problem is caused by a Cyco additive, going to eliminate them, just going Reiziger Range, just brought their grow mineral additive). I also brought Great White and Auxinone so I’m going to drain my res and refill with 20l of water,
Reizeger Grow A+B
Reizeger Grow Booster,
Great White,
and see how the pH reacts over the next 16 hours before their daily feed. Then monitor for next 3 days (20l will do 4 days feeding).
Cheers bro.

I wouldn’t think to much air would be a problem or cause one, but I’ve heard of crazier things happening. Personally I think it should help. But like I said I’m not pro.
Just a question were you haveing these problems before useing the automated watering system?

I would have to say no due to growth difference. I’m under the impression more air = more o2 for the roots.
Last grow before going auto I would make up 20l for 3-4 days feeding, set the pH and never checked it, but I never had a problem with my plants, especially as noticeable as what I am having now, but I wasn’t using some additives I am now. This has got a few heads scratching!!
It definitely has something to do with my nutes (it bloody has to), hence I’m going to change to the 1 brand, Reiziger (mainly), over Cyco with its 15 different bottles of additives, which like a sheep I brought, and now have a couple hundred of nutes I'm pushing aside and just spent more !!
Lets see how my new mix is going to react.
Reiziger Grow A+B
Reiziger Grow Boost
Auxinone (just given by my local to try)
Great White
Canna Rhizotonic
Cross your fingers for me!!

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What is pH Perfect? Nutrient brand?

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Yes it’s a brand . And from what I understand it’s a stabilizing agent. Set ph to what ever and add ph perfect. No I haven’t used it just something I’m learning about, but a lot of people haveing your problem say it solves it. Just a suggestion not telling you to buy it or anything just check it out. Keep me post on progress topics like this really interest me.

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All good bro, when I asked about it at my local store he didn’t know about it, only the brand and only some of it’s range. I’m going to check the net about that brand…
We have found a product that is supposed to stabilize the pH for up to 10 days, forgot the brand already, but it’s ordered!!

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in 9 hours the pH has gone from 5.8 to 6.9. HOLY SHIT!!!
That Water’s GONE!!
Mixing new batch as we speak.

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This the product I’ve ordered.

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Might get that my self

I was having a similar problem with an aeroponics system earlier this year. @Donaldj taught me that if I where to raise my PPM to 600 or greater that my PH would stabilize and it did. Not sure what your PPM is but you could try that

Please don’t take this wrong, but if it is the Nitrogen and Iron (just an example) that are having a pH reaction adding more to get my ppm up will not help my pH situation, but possibly make it worse, theoretically, but theory is not always right, right??!!
Another thing that I have found out is the E.C, TDS ppm C.F etc have so many charts that I have 3 pens that read 3 different TDS tables and use the easiest for me to follow. E.C, except mine is in us/cm so 1.3 shows as more acurate 1372.
Thanks for your help bro.

This is worse than metric to imperial!!