Conductivty climbing, ATO is functioning???

[byron]

sort of repeating a post from over on my build thread, but you guys may not see it:

an issue I'm working on a new tank build is that conductivity is slowing climbing evern though I have ATO running... haven't got handle on the one yet.
DT: 465g, fuge: 125g (150g Rubbermaid), sump: 125g (150g Rubbermaid)
Barracuda pumps sump to DT, but has tuneable bypass to fuge
DT is gravity drain to sump, but has tuneable bypass to fuge
fuge is gravity feed to sump
ATO is a time based Apex driven feed by a 50 mL/min BRS dosing pump from the RODI storage tank and it is keeping water to the "filled" line in the sump.

I'm topping off to a line in the sump -- which should be sufficient. I not sure how the DT or fuge could dropping low with the sump holding steady because water always seeks its own level.

But, somehow, something strange is occuring that that I'm not yet recognizing. I'm not a fluid dynamics guy, but it would seem to me that if I refill the sump to the "start" line/level, that water volume should be staying constant, within reason.

The fuge is tuneable both on entrance, so maybe its the culprit -- I do periodically still dork with the various gates and ball valves around the system... still nooding through this. I do need to put a powerhead in the fuge because it probably has dead spots, but I dont see how that contributes to this problem.

After a 40g water change on Sunday, the system read 34.7 and its now up to 35.4.

Tank still has nothing in but a bunch of snails -- its just coming up now and I dont know its personality yet.

BTW, it is possible that I got a masked conductivity reading after the water change. It may be that I was reading the new water and as 40g mixes with other 710g over time, the effect of the new water is neglible??? The salt water reservoir was reading 34.7 when I did the water change -- and the conductivity probe is in the sump and the water pumps into the sump.

btw, I'm doing 5% water changes weekly because my storage tanks are only 65g (salt mix and RODI)

(I tried to reread this for typos, but I cant get the spell checker to work :squigglemouth: - sorry for the ones I've missed)

 

[revsgirl]

:bump2:

 

[byron]

Revsgirl, thanks for the bump... I think I got an answer, posted it over on the build thread.

 

[revsgirl]

Well, good!

 

[WillKatt]

Are you accounting for temperature? I think you said in your build you use the milwaukee MA887. I use the same unit and you must calibrate or zero the meter every time you use it. Also if your ro water and saltwater are not the same temperature you need to let the sample set on the metal ring long enough for the temperature to adjust to the device or it will throw off the reading. Sometimes I have to hit the read button three times with about 30-40 seconds in between so the device dosnt time out to get a consistant measure and it will often vary something like 1.027 to 1.026 with in in a single sample before if finally settles. This is the same degree of variance you are seeing with 34.7 and 35.4.

Be sure to account for temp. It's nice that the unit has the thermometer built in but it is not immediate at best it uses ambient temperature and you need to let both the calibration sample and the seawater sample sit on it for several minutes.

 

[byron]

thanks for the tips... I will keep that in mind

btw, I do zero each time I turn it on with RO, but I have not run calibration fluid on it in the past 30 days

I'm not sure how good the meter is compared to other equipment, but it seems to work fine...

 

[WillKatt]

I love mine! I will never use anything else unless something better comes out. It's not as convenient to use as a regular refractometer but once you figure out its little quirks I think it's more accurate. One other thing you probably already know this but don't use the same pipete, syringe, what have you for both the calibration ro and the test sample and be sure to rinse the pipete for the test sample thoroughly after each use so you dont get any left over salt residue contaminating the sample.