I have grown orchids under 400W metal halide bulbs for six years. For several of those years, catts were the type of orchid I was primarily growing. Eighteen inches from the top of the leaves is really quite far away for catts. You are getting good advice from the posters above -- the black spots you have are not burn from the lights, and are most likely rots. acclimate your catts to the higher light by starting them further away from the lights and gradually moving them closer every three or four days or so. Leaves should feel cool or barely warm to the touch. Any orchid in light that is too strong can easily burn in an hour or even less. As Calvin pointed out, light that is too strong causes the leaves to turn a harsh yellow. Actual burn might be white or could be mushy brown, but would appear on the flat part of the leaf exposed most directly to the light, not on the edges. As to why the spots should suddenly appear when you first put them under lights-- probably just a coincidence. Rots always seem suddenly to appear out of nowhere. As you suspected, rots are more likely under lower light conditions. Prevention includes higher light and more circulating air. So you are increasing the light just in time. You have to watch closely to make sure the rot doesn't spread. It can spread very fast. Spray the plant with a dilute solution of Physan 20, or gently rub cinnamon on both sides of the leaves. You might have to cut off the affected portions if it continues to spread.

I think you guys are confusing the ill effects of over-heated roots with sunburn. There is little question, since plumerias grow in full sun in equatorial regions that they will tolerate any sun load North America has to offer, including TX. What they WON'T tolerate is the inhibition of root function that comes with over-heated roots. Photo-oxidation (aka sunburn) has little to do with ambient air temperatures. Sunburn is caused during high light intensity levels w/o adequate amounts of protective pigments present. This causes chlorophyll molecules to rise to a more excited state than normal. If light levels are high enough, the energy that is released as electrons in molecules return to their normal energy state may be sufficient to form oxygen (O2) radicals from regular O2. These O2 radicals are extremely reactive particles that readily destroy chlorophyll and other organic molecules. (This is the same O- radical that causes rapid oxidation [bleaching] when we apply H2O2 [hydrogen peroxide]). Evidence of the process is seen in a bleached or whitish/tannish/silverish appearance covering large areas of the leaves, and is also often referred to as peroxidation. The symptoms of sunburn occur randomly on the leaf. If you have burned leaf tips and margins, it's not sunburn. There is also confusion about what a soilless mix is. A soilless mix is a soil that doesn't contain a mineral fraction, so MG, MGMC, and almost all other soils from a bag are soilless mixes. The only two things that would make one soilless mix "hotter" than another are it's color (darker mixes would have more passive solar [heat]gain), and it would have to be exposed to direct sun for that to occur; and evaporation, with the more highly aerated soils being cooler because of evaporative cooling. Taking this a step further, soils like the gritty mix, even the 5:1:1 mix are going to be cooler by several degrees, simply by virtue of the fact that more water evaporates from soils with higher rates of gas exchange. So, it's not a technical issue that hinges on word play when we observe that Texas sun doesn't burn foliage, it's the heat (not the light). Everyone has their own little tricks they use to keep roots as cool as possible, and I won't elaborate because it's been discussed so frequently, but the goal should be to provide as much sun as you can while keeping root temperatures within a range that allows normal root function ..... which leads to some considerations about how not to keep root function at optimal levels. One way to ensure problems with foliage is to inhibit root function. Many growers seem to be too eager to give up aeration for the additional water retention offered by soils like MG and other bagged mixes that are exceptionally water-retentive. There should be no reason to disagree with what's in the following two paragraphs because all the bases are covered. Growing in containers is about perspective and balance. There is no sense in my arguing a point from the plant's point of view when someone is approaching the issue from the perspective of grower convenience or their ability to provide ideal conditions. We all arrange our priorities in a way that allows us to best enjoy life, and who should judge how we arrange our priorities? If a grower has time or can only manage to water once per week, then the grower MUST use a soil that holds enough water to keep the plant's water needs met for the duration. That satisfies the grower's prioritization, but the plant isn't going to like it. That's simply a fact we need to acknowledge and go on from there. Growing is also about balance. As mentioned, some growers THINK they need to use heavy soils that lack aeration and impede root function to get the water retention they need to get through the day. If they do, that's fine, but the fact is, these soils still do impair root function - even if they are completely necessary. Balance comes into play when we make conscious decisions based on our knowledge of soils, decisions that take into consideration how much inconvenience we're willing to tolerate in exchange for increased growth vitality in our plants. No one cares or judges you for the decisions you make re. how much time you can devote to your plants, but let's recognize there ARE decisions to be made and they DO affect our plants. By adopting a highly water retentive soil, a grower is actually putting the goal of providing an adequate water supply to the canopy further out of reach. It may be necessary to make that compromise because of prioritization, but the simple fact is, heavy soils make it HARDER for the plant to move water to the canopy and cause spoiled foliage - starting mainly with the most distal parts - leaf tips and margins. The reason they (heavy soils) are chosen doesn't matter and doesn't change their impact on the plant - it is what it is. I have no stake in what other growers use as a soil, but there are some things to consider. I mentioned this upthread, but it's important enough to repeat: Uptake of water and nutrients isn't a passive or energy-free process, it's energy driven and adequate aeration is a key ingredient, without which the root system cannot carry on transpiration, which is the energy-driven process on which the uptake of water/nutrients depends. From this we can clearly see that it makes good sense to try to maximize water retention while minimizing the negative impact that almost always has on aeration. We want the best of both worlds, but some combinations of soil ingredients simply make it impossible to have both. A perfect soil would be made of particles large enough that no perched water is held in macro-pores to inhibit root function, and would hold all of it's water inside the particles and in the interface area where particles contact each other. That's exactly the model the gritty mix is based on. If someone has a better model or can even conceptualize something better, I'd like to hear it. That's not me being bristly - just trying to get you to think before you disagree. A few growers here have indicated they don't think they get enough water retention from the gritty mix, yet I have several friends in TX and SOCAL I've been helping with their figs, citrus, and other fruit trees in the gritty mix for years. This isn't a commercial for the gritty mix, but there is no reason it won't work in TX for plumerias if you take advantage of its adjustability for water retention and build more into it when you make it. The advantages are a much greater improvement in aeration and root function that in concert work together to help roots move water more efficiently. ANY well-aerated soil increases root efficiency and the plant's ability to move water/nutrients, and any poorly aerated soil, especially those that support significant volumes of perched water, inhibit that ability. Period. Wishing real hard doesn't change that fact. No matter where a grower lives, the best shot at having containerized plants that grow as close to their genetic as possible includes a soil that maximizes aeration first, and then compromises a part of that aeration to provide the grower with watering intervals he's willing to tolerate. Plants in soils that REQUIRE watering twice each day have greater potential than plants in soils that require a single daily watering have greater potential than plants in soils requiring water every other day have MUCH greater potential than plants in soils that only require watering weekly ..... I truly hope this effort on the forum's behalf is viewed by all as helpful. Al

A Richard ergo grip safety razor scraper is what I reach for first when cleaning any Ceran cooking surface. I run the blade over the entire surface, just like a wood plane, using both hands, from one front corner to the other. Then I lift the blade, go back to the start and shift over to the next "lane" and keep doing it until finished up on a lane from back corner to back corner. When the blade tells you it is finding something "good" to work on lane after lane it is useful to flip the razor over every couple of lanes. Also try scraping any areas that gave the blade a hard time earlier from front to back as well when finished to check that the resistance is gone. I know someone whose motto is: "A Ceran top and politics have a lot in common, both can seem quite clean but when you start scraping them you may be surprised at what shows up". Cerama Bryte should be the last cleaning step, not the first, and it should be buffed away before it is completely dry. There are quite a few substitutes like the eraser in a pinch. Vim works well but don't let it dry on you, and it leaves oily streaks that will buff away after left for a day or so or go away eventually on their own. A lightly moistened strong paper towel used with a bit of sprinkled flour is also effective.

I had a feeling it was Chinese. The Chinese use a different manufacturing method than the Breton Technology used by Cambria, Caesarstone, Silestone, and the other big manufacturers. When I bought my Pentalquartz, which is Breton-made in Vietnam, the warehouse manager told me that the owner of Pental, which is a big west coast granite company, went to China to see their manufacturing facility, and he wouldn't buy it. He said the resins are cured at lower temperatures for shorter time periods. So there's the cost-savings, but it's not as durable. I've read here of surface pitting with Chinese quartz. That's unheard of with Breton quartz. So now we see your water marks, which is ridiculous. I would have them take that junk out and buy a reliable brand of quartz myself. I'm saving your photo to show others what can happen when they buy Chinese. They never believe me that Chinese quartz can have problems. They just look at how pretty it is and how much money they save.