I’ve been working on the final initial build steps over the last week and as of today that phase is complete. The RODI station is fully plumbed to the new tank and the ATO has been running for a couple of weeks. These last two weekends I have setup the auto-fill for the RODI and the AWCs (one for each tank).
The ATO is the same build as my smaller tank - FMM in the tank stand and PMUP in the remote RODI reservoir. As the run to the new tank is about 12 metres I had to cut and extend the PMUP cable, and used 2.5 mm electrical cable (as typically used in a boat or car). The joints were soldered, covered with electrical tape and then shrink-wrap tape applied over the top for a clean secure finish. The PMUP cable, along with 3 RO lines (1 for ATO, 2 for AWC) run through 25 mm electrical conduit along the side of my house to the RODI station.
The ATK is then fit inside the stock ATO reservoir and programmed to fill daily at noon. As I have had an ongoing issue with the FMM failing and needing a power cycle to bring it back online in the small tank I have programmed a VO to alert me if the ATO doesn’t run each day.
The AWC is based on two DOS heads, one for the smaller tank and one for the new tank. In the RODI station I have a 240 litre reservoir for RODI and a 100 litre reservoir for SW.
I have an FMM in the RODI station, a magnetically mounted optical sensor in the SW reservoir for high level and a PMUP in the RODI reservoir to fill the SW reservoir. Also in the SW reservoir are the two AWC fill lines (one per tank) and an Eheim CompactON 600 mixing pump. The SW reservoir has a plastic tape measure fixed to the inside so I can tell how much water is in it. Normally I will fill it to around the 90 litre mark and complete a water change in both tanks at the same time but I want the flexibility to lower the high level sensor for a short fill to just change water in one tank.
Yesterday I calibrated the SW reservoir by pouring 10 litres of water at a time and noting the level on the tape measure it reached. When 90 litres went in I turned the mixing pump on then added 3.6 Kg salt. I estimated I needed 3.8 Kg but wanted to be sure. This morning I checked salinity and it was 1.023, so I added 200g more salt. After mixing and retesting salinity was where I wanted it, 1.025.
Right now a 24 hour AWC is running - 25 litres in the smaller tank and 50 litres in the larger tank. After that finishes I’ll see how much height of SW is left - there will be 15 litres but I’m not sure how deep that will end up. I’ll use that to tune the amount of water I use for future water changes. In between water changes (6 weekly normally) I’ll refill it with RODI at least partially to give me more water on hand.
The RODI auto fill is running, but not complete, so I’ll detail that in a later post once I finish it (waiting on final parts).
Here is the RODI station and the tank as at today. I have a Lawnmower Blennie in QT currently who will go into the tank tomorrow.
