abcha0s' 300G Ultimate Reef

[abcha0s]

Originally Posted by Delphinus

(Flow should get better over time as the sand starts to get a biological film over the grains.)

Wow that is quite the writeup for water changes. Neat ideas!

I suppose an alternative to flow meters on the peristaltic pumps you could install high and low level sensors in the sump? If one of the pumps failed, blocked or otherwise became out of calibration it probably wouldn't take long for the sump level to rise or fall so a few float sensors in there might be a simple approach ?

Thanks Tony!

The challenge with level sensors is evaporation and ATO. It would work if the pump taking water from the tank failed. I think the rate of water change would exceed evaporation and the water level in the tank would slowly rise. However, if the pump adding new water to the tank failed, the ATO would keep the water level constant.

My current plan is to observe the system using a salinity probe. If either pump fails, the salinity should drift. If the calibration of the pumps is not perfect, the salinity should drift. I have no plans to use the salinity probe for control, but it should provide a good indication of the CWC operation. I may use it to automatically shut the whole system off if something doesn't look right, but the rate of change should be small enough that I can manually react long before a real problem arises.

My only concern with the Salinity probe is getting a stable reading. When I tried this on my 90G tank, I was never successful in getting an accurate and stable reading. If the probe drifts on it's own, it won't tell me anything about the operation of the CWC. The initial calibration doesn't have to be exact, but the measurement will need to be 100% stable. I'm hoping that I can find a way to achieve this with the newer hardware and a better understanding of how the probe works. We shall see soon enough

The system is working well for me now, but there's probably some minor improvements still to be made.