Hello Josh,
It is nice that you are becoming observant and you have identified the problem. 🙂
However, if you are using RO or rain water, there is no need to use any dechlorinator. RO has a patron with activated carbon that will do the job (Make sure it is in the system and replace it properly otherwise your RO membrane is at serious risk). If you prefere to use tapwater to prepare the acidifying concentrate for the RO water, dependent on your tap you should be able to use it after like 1/2 hour if it is chlorinated by gaseous chlorine or it is better to not use it at all if there are some chloramines in it for example as they could create some harmful substances together with the peat, that could stay in the water. In such case, for small volume of “normal” water, you could use RO and remineralize it with for example Sachem Equlibrium. You can drop such water over peat to get similar kind of acidifying concentrate too. I hope my explanation is clear 😀 You only need to dechlorinate big volumes of tapwater for normal tanks, if you are dealing with some badly chlorinated water or you have no space and time to let it sit for a while.