Using DOS AWC to Raise/Lower Salinity

[cpllongjk]

I just bought a Neptune DOS and Conductivity Probe for use with AUTO water changes and I have a few questions:

1. I set the NSW to ADD and at a rate of 3500mL / day split over the whole day.
2. I set the OSW to Remove and at a rate of 3500mL / day split over the whole day.
3. I calibrated both pumps and even though I wasn't able to calibrate the OSW one both pumps read 40mL exactly.

4. If I wanted to use my salinity probe to add NSW or turn off the NSW to allow evaporation and lower the Salinity how would I add those commands.
5. I don't want to keep adding salt water until the salinity rises too high, I just want to dose say 50mL, wait a bit, dose another 50mL... so on until things stabilize.

Can you Advise Please?

[reefwiser]

I have seen people set up systems using the conductivity probe to do this. But I wouldn't recommend relying on it. conductivity probes can drift and give false readings without constant checking so. You are better off doing it manually. For safety's sake.

[cpllongjk]

Thanks Reefwiser.

I actually figured out what to do. I put a safety feature in the DOS Power Port... to turn off power if the SG goes outside my specific range. I think this is a better use of it so I don't have any issues if I am away, a small safety feature.

[kurt_n]

I think your safety feature code is giving you a false sense of security. Two things can fail with this setup, the probe and the outlet. If the probe fails or even drifts and reports a false reading which is still within your range, it's going to keep pumping water. And if your outlet fails, programming doesn't matter - it's either going to be completely on or completely off.

I'm not knocking the DOS, just saying that using any device to top off your tank - that's driven by an electronic conductivity measurement - is probably not a good idea. In my mind, it's kind of like using a meat thermometer to take your temperature. It can do it, but there's other tools better suited for the purpose.

[cardiffgiant]

I agree with the risk on the conductivity probe wandering, but the risk on the outlet is something that we all face if we run top off and dosing pumps from a controller. However, unlike a normal dosing or top off pump, the pumps in the DOS are controlled by the device and not by turning the outlet on and off.

What cpllongjk is doing actually adds an extra layer of redundancy in the event that the DOS wouldn't turn itself off.