Such setup will make your trips last longer, you can expect runescape 3 gold 10+ kills per trip with such setup, runes pouch with high alchemy will help you to save some inventory slots for Hydra bones, or additional supplies which being dropped by Hydra quite often.
If you have completed elite Kourend & Kebos diary achievements, you can swap your boots of stone with any other boots which gives you ranged attack bonus. Pegasian boots is the best option which will cost you around 36M OSRS gold.
If you can afford it, Twisted bow can be a handful tool to increase your damage to Hydra. Although, this bow will cost you over 1.1B with current price and will only increase your kill counts per hour by 2 kill counts. (according to PVMER woox)
How to get there:
You can find Alchemical Hydra in Karuulm slayer dungeon. This dungeon is located on Karuulm mountain, which can be reached by Rada’s blessing teleport (after completing hard Kourend & Kebos diary), fairy rings (teleport code C*I*R) which will get you just south of Karuulm mountain, or skills necklace which will get you near Farming guild.
Once you enter the instance, she will attack you with one of the styles for 3 times in row, then she will switch to next attack style. You must flick your prayer protections accordingly to her attacks! For example, if upon entering the instance she will hit you with mage attack, you should protect mage, then after 3 attacks switch to ranged protection and so on. Because of this mechanic many PVM’ers are joking that counting to 3 is the key skill to kill Hydra, because once you will get used to other mechanics, killing Hydra will be as easy as counting to 3. But there are few more things you need to know. Hydra has 4 different forms with unique special abilities, but these forms are easily predictable and are easy to counter. At first, Hydra will always come in green form. You must lure her into red chemical pool to decrease her chemical defences. Therefore, always start instance by running to Eastern wall, this should position you for easy first quarter of the kill:
She will use her special attack after 3 basic attacks, then she will continue attacking with basic attacks for 9 more hits before using her special attack again. For example, she hits you with magic attack for 3 times, then she will use her special ability, then she will be hitting you with ranged. Very important! This special attacks rotation is the same to every Hydra form! After you will lower her hitpoints to 75% she will transform into blue form. For this step, simply run to northern wall to lure her into green chemical pool to decrease her chemical defences: