That's big enough at 30l, there could be a problem with it though which I have come across. Pull the tubing out of the head , it should be round. When I had a problem with my TDS not going down I found the tubing to be out of shape, it was shaped oval. If it is then you need to cut that bit off and then put tube back in.
You will also find that your resin is spent as the atmosphere would have got into your resin so you will have to change it.