Healthy plants yellowing

[Celtic67]

I've recently started using sulfur to lower the ph in my blueberry pots, I've read that it's micro organisms such as bacteria in the soil that break the sulfur down and the waste product is sulphuric acid. It's got me wondering if there is a way to encourage these "organisms", sugary water maybe?

 
While many sulphur reducing bacteria (the ones you are after) will feed on simple sugars if given the chance to, chances are adding a "sugary water" will most likely feed other species much better equipped to feed on the simple sugars. The best way to encourage these by adding a food source will be adding sulphur as only they will be able to feed on it and not get out competed for it by other bacteria as will most likely be the case if you add sugar.

 

[Straticus]

I have heard that using aluminum sulfate provides immediate effects to the soil PH, but can be rather dangerous. Once I can confirm the PH levels are high in alkaline in my pots I will decide on going a more drastic measure. I cant' afford to wait for months at this point, as the growing season will come to end here most likely before the elemental sulfur even starts to work. 

 

[nzchili]

I have heard that using aluminum sulfate provides immediate effects to the soil PH, but can be rather dangerous. Once I can confirm the PH levels are high in alkaline in my pots I will decide on going a more drastic measure. I cant' afford to wait for months at this point, as the growing season will come to end here most likely before the elemental sulfur even starts to work. 

 
Correct, you can use aluminium sulfate for immediate results.
The other(perhaps safer) option would be to re-pot your plants into new soil. Look for an "acid mix" type soil

 

[Hot Mama Bearz]

Dunno your problem, but here is what I would do.. I would fully water those plants with a liquid fertilizer that has calcium. You need a fast emergency treatment here. Don't stop pouring until it runs out the bottom. Then I would spray all the leaves very heavily with an epson salt solution. Do both at dusk.

With outdoor plants, I feel that folks are soo over concerned with over watering that they under water. I think peppers in pots can only rarely get too much. As long as the pots have a layer of rocks on the bottom and plenty of holes on the bottom also. If not, than that is how you really do over water....

Ps. I save rocks that I dig up from my garden to add to pots. Always keep a couple buckets handy outside even in the winter. I know some rocks in the garden are beneficial, but my house was sandblasted into it's lot.