I bought what was suppose to be a dwarf lemon tree

Question

Neither Home Depot, where I bought it, nor any local nursery can assist me. A cousin suggested it might be a Pomelo. It is not sweet and not very moist inside even though during the summer we have been watering it twice a day early morning and late evening. It is very hot and dry here. It took 8 years before it bore any fruit and they stay green on the outside. The tree is covered with thorns. Can you help?

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Answer 1

Here is a link to a photo of some additional fruit of the tree. https://www.facebook.com/photo.php?fbid=10207302927193456&set=a.10207302926873448.1073741832.1293420073&type=3&src=https%3A%2F%2Fscontent-lax1-1.xx.fbcdn.net%2Fhphotos-xtp1%2Fv%2Ft1.0-9%2F1506863_10207302927193456_8847922434055901451_n.jpg%3Foh%3D6b4c5c2c7e8c4be27d1ff8c170ff3f58%26oe%3D565977A3&size=922%2C692