Very interesting Arionum coin, i like the transparency and especially no premine, i hope, this new cryptocurrency can compete and show positive results, i think it will be good if you plan gpu mining in the future, i wiill keep an eye on this.
The whole concept of mining ARO was to be CPU only and whilst guli did some really excellent work developing a GPU miner we decided to hold a vote between the ARO mining community and what they essentially wanted.
It was pretty unanimous that GPU mining was not wanted and this also reinforced our original concept that ARO would only be a CPU only mine-able coin. As such a hard fork took place at block 10800 and updated algo's meant that ARO is now GPU resistant. You can still use a GPU using guli's miner, however you are likely to get less hashing power than an average CPU. ( A recent test carried out using several different models of Nvidia card, namely GTX 1050, 1070 and 1080Ti confirmed that hashes per second were less than 1.5 in all cases).
I hope this clears up any confusion.