Splitting Watermelons

[boats4906]

I have been growing Watermelons in my garden ,, they made it to a softball size then one of them started to split. I have read that too much water / too much heat may be the cause.. I live in Texas and I am unable to control the heat problem .. but i can control the water.. not sure how to regulate the water... turn off the water or make a slow trickle

my water tests is as follows 

using the api test kit 

ph = 7.6

ammonia = 0.25

nitrate 40

nitrite 0

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[Rex Byrns]

I am down in Victoria. About the heat, get a shade cloth. It is worth every penny. Next, your ph is way too high. I run at 6.2 - 6.4. Let it get there slowly and then try to keep it there. The recent rains that I am getting can split mellons if they get hit in the heat. Just my guess, but I would be surprised if too much water is the problem, the best I ever had were grown in a river bottom where the sand was constantly saturated.
Good luck