controller to control salinity
- Thread starter jon1985
- Start date
I was hoping to use the salinity probe to tell the RKL to turn on when salinity raises above a certain value and to run until it drops to the correct amount. Obviously the probe would be in the same section of the sump as the ato so there would not be a huge volume of water to correct. This would mean the ato would cycle on and off fairly regularly but add a fairly small volume of water each time keeping the salinity very consistant.
cr500_af
New member
The only person I know who used it effectively owned an LFS (1000g and 1500g systems). He used RKE's, and the controller was programmed to top off from RO water if SG was above 1.024 and to top off from SW if it was under 1.024. I don't know the programming he used, though. It was a blessing in his store because, unlike our systems, he was constantly bagging corals throughout the day, and with an RO topoff only, the SG would drop enough to matter.
D-Nak
Active member
Out of the box, the Apex has probe inputs for temperature, pH, and ORP. You can get a Probe Module 2 that has an input for a conductivity/salinity probe. I thought about getting it as a back-up for the ATO (if the salinity is low, it turns off the ATO) but I found it wasn't necessary. As with all probes, all they do is monitor -- you have to program your own parameters -- so as long as the conductivity probe is monitoring accurately (never researched how accurate these things are) can have Apex control whatever you want. My guess is that you plan on having a container of RO water for top-off, and one of high SG salt water to bring the salinity up if you need it?
I'm having trouble wrapping my head around this one. I understand that you skim wet, but do you skim so wet that you feel the need to add salt? For most folks, a simple ATO is fine to maintain specific SG. Do you use 2-part for calcium supplementation? If not, maybe you could do that to counteract the salinity change?
I worry that if the conductivity probe should fail, you could nuke your system, depending on how you have it set up. Sounds like an awful lot of trouble. Maybe just skim drier? (I kid, I kid.)
I'm having trouble wrapping my head around this one. I understand that you skim wet, but do you skim so wet that you feel the need to add salt? For most folks, a simple ATO is fine to maintain specific SG. Do you use 2-part for calcium supplementation? If not, maybe you could do that to counteract the salinity change?
I worry that if the conductivity probe should fail, you could nuke your system, depending on how you have it set up. Sounds like an awful lot of trouble. Maybe just skim drier? (I kid, I kid.)
d0ughb0y
Active member
I agree its too much trouble for very little return.
how wet do you skim? I mean, how much wet skim do you get in a day?
I don't know your tank size, but say if its 180gallons, you need to skim out 7 gallons for SG to drop 0.001.
easier to adjust the SG during water change.
ok, I see you said you are off 2-3 points at the end of the week. is point SG or ppt?
if it is ppt, thats 15 gallons wet skim from a 180 gallon tank.
you can compensate using your top off water.
say if you know you wet skim 15 gallons, but you top off 25 gallons, you know 10 gallons is from evaporation. you can mix 25 gallons of top off water at 21ppm.
how wet do you skim? I mean, how much wet skim do you get in a day?
I don't know your tank size, but say if its 180gallons, you need to skim out 7 gallons for SG to drop 0.001.
easier to adjust the SG during water change.
ok, I see you said you are off 2-3 points at the end of the week. is point SG or ppt?
if it is ppt, thats 15 gallons wet skim from a 180 gallon tank.
you can compensate using your top off water.
say if you know you wet skim 15 gallons, but you top off 25 gallons, you know 10 gallons is from evaporation. you can mix 25 gallons of top off water at 21ppm.
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I would STRONGLY recommend against automatic salinity corrections. Anything that gave a false salinity reading could cause the tank to skew way out of desired ranges.
One easy way to get a false reading is if anything, from algae to a chunk of detritus to CaCO3 deposits that get between the electrodes will cause the salinity to read falsely low, causing you to boost the salinity artificially high.
One easy way to get a false reading is if anything, from algae to a chunk of detritus to CaCO3 deposits that get between the electrodes will cause the salinity to read falsely low, causing you to boost the salinity artificially high.
D-Nak
Active member
My point exactly. If anything, the conductivity probe should be programmed to turn something off. I would only use it as a fail-safe mechanism. I suppose if you really want to do it, you could use two conductivity probes, one as a fail-safe. But now I think we're getting into that whole "Rube Goldberg" mentality where we have a lot of parts to do a simple task.
schoch79
New member
Though many people have said don't do this I think it is a great idea. Granted there are variables like if it is reading improperly but I just see this as another safety measure. So many times you hear of ATO's getting stuck on and ruining a tank. A controller to turn it off so it doesnt stick on sounds great to me.
Turning off an ATO, as mentioned, is a fine plan, as long as you are alerted to it as well so you can check to see if it is a correct action. Turning on anything, either fresh or saline, is not a good idea.
In general, it is not a good idea to even keep a salinity probe in the water 24/7. It will likely get coated with stuff and become inaccurate. Just look at what other stuff in your tank looks like after a few weeks in the water, and imagine that stuff between two electrodes trying to pass current between them to sense salinity. Some of this issue is mitigated by frequent cleaning of the probe, but not all of the risk.
I discuss how such measurements work here:
Using Conductivity to Measure Salinity
http://replay.web.archive.org/20040...iumfish.com/aquariumfish/detail.aspx?aid=1804
and give some DIY calibrations standards here:
Reef Aquarium Salinity: Homemade Calibration Standards
http://reefkeeping.com/issues/2004-06/rhf/index.htm
In general, it is not a good idea to even keep a salinity probe in the water 24/7. It will likely get coated with stuff and become inaccurate. Just look at what other stuff in your tank looks like after a few weeks in the water, and imagine that stuff between two electrodes trying to pass current between them to sense salinity. Some of this issue is mitigated by frequent cleaning of the probe, but not all of the risk.
I discuss how such measurements work here:
Using Conductivity to Measure Salinity
http://replay.web.archive.org/20040...iumfish.com/aquariumfish/detail.aspx?aid=1804
and give some DIY calibrations standards here:
Reef Aquarium Salinity: Homemade Calibration Standards
http://reefkeeping.com/issues/2004-06/rhf/index.htm
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