I need help with pH adjustment (Flushing)

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Ok so recently found out that ive been watering my plants 7.8 pH water and they have started to die on me.

I started to flush with phed water at 6.5 but the run off stayed 7.4
after a few more flushes it went down slight but took ages.

By adjusting the ph of the water i was flushing with to 5.0 after a few times it brought it down to 6.8 then i watered with a ph of 6.5 and it stayed at 6.8

Is this normal ? Am i doing it wrong?
 
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Here is something I have been reading recently, maybe this will shine some light on your situation, compliments of Premier Tech Horticulture. Of course, if you are in soil you will want your ph higher than their recommendations but this gives you an idea of how to adjust ph. Hope it helps!

Perfect pH
Thursday, April 25, 2013
A Word About pH and Nutrition

Ideal pH: The starting pH range for most PRO-MIX products is between 5.4-5.9. After watering and using fertilizer, the pH of the PRO-MIX is fluid and can change. Ideal pH for most crops is 5.5-6.2. If pH is higher, micronutrients become unavailable to the plant causing yellowing or distortion in new leaves. If the pH of the growing medium is lower, micronutrients are more available and if taken up in excessive quantities can cause leaf edge burn on the lower leaves.

Testing the pH of a crop: pH is best measured using the saturated media extract method (growing medium is removed from the root ball, distilled water is added to saturate the growing medium sample and the pH and salts are tested from the mud after 30 minutes). Some growers use a pour thru method, where a measured volume of distilled water is applied to the growing medium and the leachate (run-thru) is collected, but it is only as accurate as the amount leachate that comes out from the bottom of the container. If too much comes out, the pH and salts will be diluted and will not accurately reflect the levels in the growing medium. If too little comes out, the salts are concentrated and the pH is often unreliable, too. To avoid fluctuations, make sure the procedure is done the same way each time and measured accurately.

Maintaining the pH of PRO-MIX : There is a lot of misconception about the effects of ‘water pH’ on the pH of PRO-MIX. The truth is that the pH of the water has no bearing on the pH of the PRO-MIX. In other words, if the pH of the water is 5.5, that does not mean the pH of the PRO-MIX will be 5.5 overtime. So what influences the pH of the PRO-MIX?

Bicarbonates: Think of the bicarbonates in the water as dissolved limestone. If it is low (<50 ppm HCO3), then the pH of the PRO-MIX will not change much because there is little limestone supplied at very watering. If the bicarbonates are high >180 ppm HCO3, the media is being limed at every. This causes the pH of the PRO-MIX to rise to unacceptable levels (above 6.5), even if the pH of the water is 5.5. Ultimately the goal is to match up the fertilizer with the bicarbonates within the water.
Many companies recommend using water that has passed through a reverse osmosis unit. Often this is an unnecessary step, but it will filter out most of the bicarbonates from the water as well as beneficial calcium and magnesium. If the unit works properly, it will reduce the bicarbonates in the water to undesirable low levels. If you use a R.O. unit, it is best to blend the water R.O. water with some (505) of the source water to achieve a desirable bicarbonate level.

Fertilizer: Fertilizer elements that are absorbed by plant roots have an electrical charge. The plant root zone has to maintain its neutral electrical charge. For plant roots to uptake electrically charged nutrients, the root system must give off and exchange elements of the same charge. Therefore, for the plant’s roots to absorb positively charged ammonium, potassium, calcium or magnesium, the roots must give off hydrogen. Hydrogen is acid and will reduce the pH of the growing medium. If the root systems absorbs nitrate, phosphate and/or sulfate, it will release off negatively charged alkaline hydroxides – which increases the pH of the growing medium.
Of these elements, nitrogen is the only one that can have an acidic (ammonium and urea) or alkaline (nitrate) reaction with the plant roots. The ratio of these nitrogen forms within the fertilizer dictates whether the fertilizer is potentially acidic or alkaline, depending on how it is absorbed and reacts with plant root systems. As a guide, many fertilizer manufacturers will list the fertilizer’s “potential acidity” or “potential basicity” which indicates how much acid or base is added to the growing medium by the plant roots. Most growers will have their water tested and then match the fertilizer to the water quality. This matching will minimize pH fluctuations within the growing medium.

Having said all this, if the water has been processed through a reverse osmosis unit it most likely will have a slight change effect on the pH of the growing medium. However, any fertilizer will have a significant influence on the pH of the PRO-MIX. The fertilizer used should supply all 13 elements (N, P, K, Ca, Mg, SO4, Fe, Mn, B, Cu, Zn, Mo) and the fertilizer’s should provide potential acidity or potential basicity. Without this information, it is difficult to determine where the pH of the growing medium will go long term.

Common Nutritional Problems

New leaves are yellow or distorted: This is often caused by some type of micronutrient deficiency. Not all micronutrient deficiencies are caused by high pH. Many times there is fear in over-applying fertilizer so less is applied, which leads to nutrient deficiencies. Also many organic fertilizers contribute to this problem as they take up to 1-2 months to breakdown and become available to the plant in a soilless media. Calcium deficiency could be the cause of the problem too if leaf expansion is distorted. Other causes include air drafts or exposure to very bright light over long periods.

Old leaves are yellow: Most likely this is from nitrogen, potassium, sulfate or magnesium deficiency. If this is occurring, pH is not the issue. It is simply lack of application of these elements. Look at the fertilizer application rates, it may be too low. Organic fertilizers often cause this problem as it takes up to 1-2 months to breakdown and become available to the plant in a soilless media. Lower leaf yellowing could also be caused by lack of light, cold air draft or watering problems.

Plants don’t grow: Likely cause is from lack of fertilizer. Fertilizer, especially nitrogen, is like the gas pedal in a car. The high the nitrogen rate, the faster the plant grows (assuming the salts are not too high). If the fertilizer levels in the growing medium are too low, the plant will not grow. This is a common problem especially when using certain organic fertilizers. PRO-MIX contains a starter fertilizer that is for initial plant development, so you need to apply fertilizer to what the plant needs. If the product is aged (9-12 months after manufacturing date) the small amount of fertilizer in the product may be used up from microbial activity, therefore you will need to apply fertilizer from the beginning.

Other common causes of nutritional problems can be caused by growing environment and include cold growing medium and/or cold air temperatures, keeping plants too wet, root disease, over fertilization, etc.
 
Ideal pH: The starting pH range for most PRO-MIX products is between 5.4-5.9.

Premier has made a lot of changes to their product line recently and I'm wondering if they have changed the base pH of their products as well. I test every bale of Pro Mix I buy and the starting pH has always been 6.9 - 7. To lower the starting pH I've been experimenting over the past year with sulfur, cottonseed meal and aluminum sulfate. I've found that sulfur takes too long to become active and the cottonseed meal adds too much N. Aluminum sulfate has worked best. When added at the rate of 4 grams of 17% aluminum sulfate per gallon of mix, and feeding at a pH of 6.5, the pH has been dropping to 6.2 - 6.3 when measured the day after feeding, then slowly rising to about 6.6 - 6.7 as the soil dries out. If they have indeed changed the starting pH of their products, then I would expect that the AS would no longer be needed.
 
They haven't yet Muddy, I just purchased a bale last week, manufacture date 8/?. So two months ago. Straight outta the bag, 6.8.
 
They are expanding more into retail as opposed to their HP and BX products, which were mainly aimed at the professional, greenhouse type growers. Perhaps they have lowered it for the retail products and left it the same for the pros.
 
Thanks A4 ! Always a man full of knowledge!

That doesn't answer my question though as I'm not feeding any nutes and using a regular multipurpose soil with no fertiliser.

As have only been feeding them plain water with a ph of 7.8 for about a week I just need to know the correct method of flushing I.e. If the ph of runoff is at 7.8 should I flush at 6.0 before it brings the run off down?

I know a little about cations and anions but at this stage I would of thort that would be irrelevant as feeding any nutes at this age (seedlings) would probably cause more problems ?
 
Yes, I understand what you are saying. The point I was making was that my recommendations has been wrong as well as what the techniques I have been using. Take a look at table one in this link, you will need to do the calculations for the amount of soil needed as well as the aluminum sulfate but that should bring it down fairly quickly with a product you should be able to purchase at any store. http://hubcap.clemson.edu/~blpprt/lowerpH.html

Other than applying some type of fertilizer or a chemical like aluminum sulfate I do not think ph lowering is achievable over the long term. I have found flushing always works for me BUT, I have always flushed with a weak nutrient solution which may explain why I have had better results than someone using just water alone. Being that the nutrients are actually acidifying the soil and not the water.

I am reading feverishly at the moment trying to understand this all.
 
Ah i see so although it being a very small dose of nutrients it still holds the relevant cations/anions to bring it down via root interaction etc..

So finding a nutrient solution which is higher or lower in either cations or anions depending on which way we need to go should still have the desired effect without burning the plant i guess?

Thanks a lot A4!
 
Or, the aluminum sulfate via creating the chemical reaction needed. It appears that the aluminum sulfate works much quicker than sulfur as it doesn't rely on bacteria to convert and adds no nutrient. See the last paragraph in that page?

Before recommending that a gardener add a material to acidify the soil, make sure the pH is too high and find out why. Perhaps using an acid-forming nitrogen source such as ammonium sulfate or sulfur-coated urea will gradually correct the problem. If not, recommend aluminum sulfate as the first choice. He/she is less likely to over-apply this material. Recommend "flowers of sulfur" only for large scale growers, and caution them about over-applying sulfur. Don't confuse elemental sulfur as a soil acidifying agent with sulfur recommendations as a plant nutrient.
 
I'm just rolling one up to indulge in that page - your a good man A4!

Cheers buddy!

PS: There is allot more to pH than just lemon juice isn't there lol
 
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