You can use a Wetting Agent to help retain and distribute the water more evenly, it's not a miracle worker but it will help a little bit. I too have straight sand and it's not as bad as you think it is. Focus on growing a thick and healthy lawn and that alone will do a lot of the work in holding on to water and nutrients. Just know that a lot of golf course greens are grown on a pure sand base and they seem to do just fine. You may be better off than you think you are.

 

Any thoughts on using hyderetain or humichar?

 

Last year I introduced wetting agents to my plan. I used wetting agents 3 times. I have wet areas and dry areas. In my dry area lawn was weak and there were some small areas that had bare soil. The area is on a grade. The water would run off instead of being absorbed. I could see a sheen on the bare hydrophobic soil. The weak lawn is some of the thickest now. The grass spread and filled in the bare spots. I have silt and clay soil but I am confident that it should work on sand based soils also.

 

I use underhill h2o maximizer with good results. I also have the tournement ready pellets. The applicator and nozzle is an investment and I only use this for spot spraying. The h2o maximizer can be applied either with a backpack sprayer or using a hose. It comes in 2.5 gallon containers and was around $90.

As @Mightyquinn mentioned, do not expect miracles. I have sandy soil as well and still need to water every other day when it gets hot. My lawn does not burn out now on the second day and does not show much stress. Before it would be extremely stressed on the second day. I haven't tried to push 3 days in between as I still feel it would only make it 2 1/2 days at best.

I also do not believe that Hydratrain can pull moisture out of the air outside of immearsureable amounts. I usually ignore marketing claims as they are greatly exaggerated.

I have used humichar and humic acid in the past and cannot see any difference. You would need to put down a ton of it to even have the possility of seeing benefits. I have since gone back to concentrating on the big 3 (NPD), mowing often, and proper irrigation. Throw in weed/fungus prevention and control and you will have a really nice lawn.

 

Both Humichar (because of biochar) and Hydretain work, but you would have to use a lot for a long time to see any major difference, and this would get expensive. In testing, using Hydretain could delay drought conditions for a day or two. So, while they can work, it is probably not worth it unless you put in a lot of money and repeat applications over time. Instead, try compost to change the soil structure over time.