Is this enough???

They actually need 1 to 3% of their desited body weight per day

Free choice hay is a given for about any horse IMO unless there is medical reason to limit it

You're not giving her enough Safe choice to meet her nutritional needs. If you want to keep feeding her that feed, you need to add a vit/min supplement to it. If you don't care about sticking with that feed, I would look for a ration balancer like Triple Crown's 30% Supplement or Buckeye's Grow 'n Win. They are an all-in-one feed/supplement that you only feed 1-2 lbs a day of for full nutrition. I'm not a fan of Purina's supplement (or any of their feed) as they are not fixed formulas and you never know what's going in to their feed...

For hay, she should be getting 18-30 lbs of hay a day (2-3.5% of her body weight), if you want her at 900 lbs. She looks a bit dainty, so she may weigh more like 800-850 for her optimal weight, which puts you at 16-28 lbs of hay a day. I would start somewhere in the middle, like 20-22 lbs a day split in to 3 meals, and see how she does with that. If she gains, cut back by a flake. If she loses, add a flake.

Without knowing how much your flakes weigh, it's hard to tell you how many flakes of hay she should have. To figure it out, it's best to know what a whole bale weighs, then how many flakes per bale. Our grass bales weigh about 60 lbs. I make sure to feed mine 1/2 a bale a day (mine are bigger though). For your girl, I would feed 1/3 rd of the bale every day, which would be about 5 flakes of my hay.

OH OH Nutrena has Empower Balance now as well :)

Free choice hay is great (and most of our animals are fed that way)- but you need to be feeding something like a #4 or a #3 hay to go free choice - and with that you have to recognize that your animal will not have a tight racehorse belly. The biggest problem a lot of people have is that they have no way to control waste and thus their horses end up using more like 4-5% daily as they make a bed out of their hay:.)

If you want that tight racehorse belly, or your animals are performing hard and cannot carry excess weight, you really need a better hay - like a #2, #1, or a Prime. Unfortunatly, unless you have a milking moma, these hays will have to be limit fed and be closer to that 1% body weight you mentioned.

Unless there is medical reason there is no reason to restrict hay and excess wieght falls into medical reason.

Slow feeders were designed for just this reason to limit the horse's ability to eat all the hay fast and to help reduce waste.

Not all of us have access to tested hay... hell my dairy guys don't even test thiers in my area

None of the hay guys I buy from test their hay either. We have a couple of big hay producers that test, but their hay is out of my budget, lol. Most of theirs was sold this year to Texas and other drought plagued states. I test my own hay sometimes, just to make sure my vit/min is covering everything I need, but not very often.

I have three horses that are too fat on our free choice hay. Two are rarely ridden and the third is a beginner lesson horse. They're okay being too fat ATM . I'm switching over to squares to see if it helps having less hay, but I can only throw out hay once a day right now, so I have to throw out more than they really need to keep them busier longer (I spread it out, 18-20 piles for 6 horses). I need to invest in some slow feeders...

You live in Southern California, and when I lived there the first cutting bermuda hay was always my choice. I owned 3 arabians, and 2 out of those 3 were very easy keepers. I think you should feed about 15 pounds of quality hay a day and offer a plain salt lick. If, and only if, you need to add something else, I would go with about 3 pounds of soaked beet pulp. I think you will be ok with just hay though, especially as a pleasure horse.

Lacey while you are covering the roughage needs in all your post you are completely missing the nutritionally aspect of feeding... beet pulp and hay alone is not a balanced diet

Nutritional meaning vitamins and minerals or fat and protein? Hay and Beet pulp have everything a pleasure horse needs. Only if this horse were being worked hard would she need a ration balancer or any additional fat that beet pulp and quality grass does not have. The only mineral west coasters need to worry about is Selenium, which you can get in a mineral block. And the calcium/phosphorus ratio in beet pulp is totally ok if the horse is getting only a few pounds a day and is not a performance horse.

Actually beet pulp is not balanced and is alittle LESS nutrition then oats

Most hays are lacking in several areas including Lysine

Without testing you can't assume that unless your horse is on several hundred acres.