This gets a little scary for me. I have been growing orchids for so long that I have convinced myself that my orchids grow better and flower better when I switch fertilizers.
Over my now 48 years I have used Miracle Grow and Mir-acid.
Then went to DynaGro
Then Peters
Then Champion
Then Orchid Plus
Now for the last several years it has been Jack's.
For the most point it has been 20-20-20 but in the beginning growing in plain Fir bark I used 30-10-10 in conjunction with a 10-30-20 I think it was.

But I believe that each and every time my plants were under performing and causing me to think about the change. They were not growing and blooming like I thought that they should. So I would switch.
As soon as I did, I noticed pseudobulbs got larger, leaves got bigger and there were more flowers.
It think it is time to switch. Perhaps they get used to a certain formulation. But if you change things up, the orchids respond.
I am leaning towards a Cal-mag fertilizer, maybe 20-20-20. Maybe something with extra micro nutrients? Totally undecided.

What is every body else using?
And has anyone else ever noticed a similar decline in their plants?

For me it is a mixed bag! Some Orchids did better, some look a bit tired. Since I grow outside over the Summer, I usually attribute this to the kind of Summer we are having. Too many really hot days and the cool growers look unhappy, warm growers rejoice. Lots of warm and sunny days - the Vandas are happy.

I'm using Sta-Green brand 24-8-18 with a bunch of micro-nutrients at the moment. Lindsey recently tipped me off to stop putting extra Epsom Salts in with my fert, so just this last week I did that. Yet to see any visible difference, but of course the weather has changed this week, from blazing hot and pretty dry to cooler, cloudy and rainy, off and on so that always makes the orchids change a bit too.

My orchids get misted, at least half the cage gets misted daily, the other half gets watered twice a week. Vandas get automatic misting every morning, and usually a good spray with the hose on days it doesn't rain in the afternoons. Both times they're watered with my high pH well water and our artesian water here has high phosphorus as well, so that's the reason I like to use a fert formulation with the lower middle number.

Have you tested your water for pH, Bill? Might make a difference what you use as fert going forward.

Yes, it was 7.1.

I think it was from Jim, that I got some advice on fertilizers. He put his fertilizer and everything else, such as Neem oil or 3in1 or whatever he was using at the time into one spray and covered "everything but the flowers" when applying. Saved me time!! He also felt that, over time, if using the same bug killer it became less potent as the bugs may develop a resistance to it after awhile. Hence he always suggested 3-4 different products for pest control.
He has the same thoughts about fertilizers. Plants will need nutrients in different amounts during there life-cycle as well as within the growing season. So rotating the fertilizer you use should help our various genera to get what they need. At least it makes sense to me. I have been following this thinking for awhile now and can see the differences when I change fertilizers. Here is what I am currently using from Norman's orchids

I am making a switch to a Repot-me fertilizer.
I read an article just today in ORCHIDS magazine where the author, with over 30 years of growing experience said that the ideal ratio for orchids is probably 3-1-3. Anything really outside of that is probably too much.
Right around 3-1-3 is what most orchids can utilize. Concentrations above that is basically money down the drain. Why boost available nutrients if the orchid root can not adsorb them?
He claimed that all fertilizers are pretty much made from the same ingredients. This includes micro nutrients. He said that the MSU feeding program is probably a good idea.
But what he pretty much said was fertilizers at a lower nutrient level if you are fertilizing often is the way to go. If you bombard your plants all the time with 30-10-10 or 10-30-20, or both, there is no way for the orchid plant to utilize those nutrients! You would be wasting your money. And if it sits in your media too long, it is probably damaging your roots.

So I ordered a pound of this water soluble stuff, I'll come back with the ratio, with MSU added might do the trick. But I have about a pound of Jacks 20-20-20 to use up so I'll switch back and forth for a little bit!
Of course I will report back to the group.

It is roughly 13-4-16 with 8% calcium and 6% magnesium. Other micronutrients are included.

Compare this to the above.
DynaGro Orchid Pro
Use 1/2 tsp. Per gallon
7-8-6 with 2% calcium and 0.5% magnesium. If cal-mag is the way to go, I was more comfortable with the above at 8% and 6% respectively.

I don't need anything with calcium in it, since I'm watering with mostly well water that comes straight out of our limestone aquifer. Going to spray Epsom salts separately from now on, as I use it on my tomatoes, peppers and roses as well.

I was using the MSU formula for quite a while but changed over to this other Sta-Green formula just this spring as it's SO much cheaper and locally available. Didn't notice any appreciable difference - the Vandas would be the ones to show it I think, since they've been getting very dilute fert twice a week through the spring and summer. I've had good root and foliage growth and fair flowering, too.