One of the most common causes of necrotic (dead) leaf tips and margins is over-watering. The mechanism by which this occurs arises from the fact that soggy soil reduces the oxygen essential to root function and metabolism, so roots are not efficient enough to move water to the plant's most distal parts - leaf tips and margins.

The TWO most common causes of poor foliage are over-watering and a high level of solubles (salts from fertilizer and tap water) in the soil. Both of these maladies are exacerbated by heavy soils that are watered in sips to prevent root rot.

Sunburn shows up as grey or silver areas on the foliage as the chlorophyll is bleached (oxidized) by the same free oxygen radicals found in hydrogen peroxide, also a powerful bleach/oxidizer. Following the short period of gray/silver blotches, foliage will turn brown, or sometimes black in plants with succulent foliage. 'Red' isn't in the realm of possibility because these oxidants would destroy the pigments that cause red coloration in plants.

I use soils that require very frequent watering - usually daily in the summer months, and I can't remember the last time I had a plant with poor looking foliage. Fast soils allow me to water copiously and flush accumulating salts from the soil each time I water w/o any concern about root rot or suppressing root function because of soggy soil. I can also fertilize frequently at reduced rates with no worries about the level of soluble salts in the soil interfering with water and nutrient uptake.

I wouldn't put much faith in the idea that letting your water rest for 24 hours is going to play a significant role in correcting your foliage issues - it won't. It's possible that chlorine (an element necessary for normal plant growth) and fluoride might be marginally contributory to your issues, but the fluoride in drinking water isn't volatile (doesn't dissipate) and nearly all municipal water suppliers are using a non-volatile form of chlorine as well. Almost all causes spoiled foliage issues can be found within the triangle formed by soil choice, watering habits, and nutrition. Unless your plants are next to a heat source (register/radiator, under hot lights, on top of a TV .....), most other cultural conditions like low humidity, chlorine, fluoride .... will be marginally contributory.

Most growers take a giant step forward in their ability to produce consistently healthy plants with the least amount of effort once they've come to understand the importance of soil choice to their success. Getting your plants into a healthy, fast draining soil that holds little or no excess water provides a foundation you can build strong plants on. Heavy soils that support excess volumes of water are inherently wrought with issues that find you fighting the soil constantly instead of letting the soil work FOR you. More on that if you wish.

I would abandon the use of any fertilizer for plants in containers that have the middle number (phosphorous) higher than either the first or third numbers (nitrogen and potassium respectively). No plant uses more P than either N or K, so it makes no sense to supply it in excess because an excess is limiting. When all the calculations are done, fertilizers in the 3:1:2 RATIO (RATIO is different than NPK %s) come closest to providing nutrients in the ratio plants actually use. This is very important when growing plants with temperamental foliage because it allows you to supply nutrients at the lowest level possible w/o nutritional deficiencies. LOW levels of soluble salts in the soil greatly increase your chances of producing plants with healthy leaves. Questions?

Al