Hoping someone can help me before I pull all my hair out.

Just put in a brand new arena.  We have awesome draining ground so no drains were needed. The native ground was taken down, leveled, and a 2% slope was done. It was also rolled with a 5 ton vibrating roller. Then inch and a quarter cleaned rock 2" deep was put down and rolled. Then we did an arena mix consisting of course sand and buckshot material at 6" deep was put down. It was way to deep so we took it down to 3-4 inches in depth which still feels deep but it scares me to go down anymore because of hitting the base. My problem is there is no binding material in it so the horse still sinks down pretty good. How do we stop this from happening? The footing was also rolled too, I feel like I need to add substance to the sand to get it to pack and keep the horse from going down through the sand??  Since I have all this nice medium course to course sand can I add dirt/loam to it and mix it in? My ultimate goal is to use the arena for barrel racing practice and conditioning.  Any help is greatly appreciated 

Covered or outside?

Water is the answer either way, but outside you will get natural water at times whereas inside you will have to bring it in.

My arena is 130 x 220 - I started with 9 - 5 axle truckloads (BIG trucks) of sand on top of the prepared base. In places that sand was 8-10" deep. I never had a problem with too deep of sand. Check out the depth at a competition arena and you will find the base at least 12" deep. Horses at full speed will need that much depth. 

How much water you need will depend on your level of activity. My favorite time for speed practice was just after a good thunderstorm and 1 to 2" rain. It was good to hold the horses for nearly a week after that. Slow work is fine at any moisture level.

The only way to have a firm surface in an arena is to not use sand. But if you're riding barrel horses you want deeper ground and ground that gives. They can't afford to hook up on a turn, same as cutting horses. That ground has to give to keep injuries minimal. Sand is ideal. 

If you are covered you could add some clay to the mix and give it a firmer feel. Doesn't work well outside unless you are OK with working it after every rain until it breaks up into power again. Clay clumps when it rains and then sun dries. After that it's brick and is a bear to try to work into small enough pieces to ride on.

It's an outdoor arena.  I must have to water and water and water to get some of the fines to settle down into the base to start holding me up off of it.  Once I have a layer that won't let me hit the base I'm guessing I can start adding more footing until the desired depth is met to be able to handle speed.  When it was 6" at first  you couldn't hardly walk on it becuse you were sinking so badly and then the horse was trudging throgh it pretty badly and I was scared of doing damage to her.  I'm curious if I add a dirt loam mixture to the sand that I have if it would help stiffen it up to give me a good base on top of the rock base I put down.  If I put 12" out there right now you wouldnt be able to even walk in it it's sooooooo loose.  

There are arena experts out there that could give you a specific clay that would work with the specific sand you have. But from what I know, clay is the best for mixing with sand for indoor arenas for non-cutting footing. Cutters use straight sand. Barrel racers like some give and some bite. 

I do know what you're talking about with the deep sand and slow work. You feel like the horse is sliding every which way every stride. One of our VA indoor arenas has more clay than sand and gets snotty slick when it is humid. The VA Horse Center has clay in it's sand mix and never gets like that. Call the owner of an arena where you like the footing and see what they used. Or call a bigger facility and ask.

Thank you so much for the ideas, I've emailed a couple different outfits that do them and rehab them.  Keeping my fingers crossed :)   

We have the same problem, but it's not the depth or moisture, it's because the contractor put in the wrong kind of sand. It's too rounded, and therefore can't pack, no matter how much water is on it. 

I have it down to about three inches, and there is NO speed work allowed. It still shifts with every step the horse takes, whether wet or dry.

After researching and checking what's in my wallet, I've come up with a plan. I will take really well composted manure and spread it with a manure spreader. The pile is more than three years old, and it looks like excellent soil. Then mix as best as possible with the sand. Hopefully I will have 6-8 inches of good, non-shifting footing.

Good luck with yours!

Soil is made of 3 types of partials- sand, silt and clay.  If you do a jar test (one cup soil and add to a quart jar-fill jar with water) you will be able to see the composition of your arena footing. You will be able to see the layers. First you have to shake the jar and let it sit 24 hours for it to fully settle. Organic matter floats to the top layer based on density. Your sand arena footing most likely has a higher amount of actual sand and came from a pure source. Masonry sand is one example as it has been washed to remove clay and silt. Clay provides a binding structure for the sand. Your local NRCS office or extension agent should be able to point you in the right direction. 

Someone mentioned using composted manure to add grip- won’t work like you think. It is still mostly organic matter that is used to “enrich” soil and improve growing ability. But not a good replacement soil. It will make mud. 

I will See if I can find a link explaining the jar test

https://www.azlca.com/uploads/documents/jar-soil-test-activity-sheet.pdf

Oh thank you for the info and jar test link, I’ll do it this weekend.  I did talk to a very helpful guy at Premiere Equine and he said the exact same thing.  I’m all sand and no loam.  He suggested I add the silt/clay/sand mixture to a small area of my arena and play with it, he felt good about the loam becoming the binding agent I’m missing.  I’m going to do the jar test though.  Thank you so much for the help ??