I got my C1900 online today. Ph read as nearly 9...I thought, that's got to be wrong, my ColorQ Pro7 test kit says it's 7.3 (been there for weeks). Gotta be a bum sensor - I expected to calibrate it, but not that much. So I tried a test kit my PB gave me. Color matching test..I hate them, I don't have great color gradient recognition. It read high as well, off the chart. Then went to the pool store. Made them test it twice. Assuming they are correct and my colorQ is wrong, my pool is pretty messed up. pH, hardness are way off. FC is also much higher than I want it (which also explains why I have had so much trouble with chlorine levels as I read them with the ColorQ)...ug. Learning something new every day.

(just ordered a TF100 with a stirrer)




Injectors:


Pumps:


C1900:


Probe Bowl...technical term :


Enclosure to protect from sun and rain:


How it shows up on Aqualink:

Finally got my TF100 today. Based on the pool store results, I had calibrated the PH. It's spot on now at 7.5 according to the test kit. I have it set at 7.5 and it seems to hold it pretty well. TA is 150 and CYA is 30. FC was 3, at an ORP of 460. It's set to 300. I notice the ORP levels are volatile, but now that I can test I'll check to see if the issue is just the dosing time being too long.

A week into it and the PH is dead on. FC is steady at 3ppm. Wish my tanks were bigger now....

Installing larger tanks is fairly easy. Your existing pumps can be moved to a new tank very easily, especially if you buy a tank of the same design.

Jason, how much did you see ORP occilate/vary on your setup. I know the gas byproduct of the cell was causing you issues, but beyond that did you see ORP move around a lot?
I'd expect it to be proportional to FC, but it does not seem to be. The system is keeping FC levels fairly consistent in the 2-3 range, but the ORP readings move around a lot, between 600 and 250.
I wish I could record the data programatically.

There weren't any wild swings unless I added chemicals near the skimmer. There would be some small jumps when the pump came on after being off for a while, but that settled quickly. At any given moment the reading would jitter around by about +-20. During the day the average would go down by 20 or 30, compared to at night. On my setup the reading would go down steadily while the SWG was on, due to dissolved hydrogen gas, then drift up slowly when the SWG was off as hydrogen outgassed, and finally, after the hydrogen was mostly gone, drift down as FC came down (if I let it go that long).

ORP is quite sensitive to PH. My PH was very stable, and it sounds like yours is also, so that shouldn't be an issue.

Here is another mistake I made, just figured out today.

When I installed my LQ, I put the suction line (outlet) before the VS pump and the intake line after the filter and UV light. The chemlink circulation plugged into the same taps.

What's wrong with this picture?

The issue (I think) is that because I run low flow rates (25-30gpm) the UV-C light is burning off a good amount of the chlorine concentration before it gets to the ORP sensor. UV-C does not destroy as much chlorine as the sun, but I guess it is still significant with a powerful UV light and low flow rates. I noticed that when I run higher flow rates, such as running water features that double the flow rate through the VS pump, the ORP level goes up. Moved the intake to before the UV light. ORP levels are much higher now.

I saw the chemical pumps and assumed you were injecting chlorine after the sensors. I didn't notice the Liquidator. Using the LQ to inject chlorine before the sensor complicates the use of the ORP sensor greatly. The LQ injects chlorine before the pump, regardless of where the other pipe is attached. That makes the FC level at the ORP sensor higher than the actual level in the pool, and the amount higher is going to vary with how full the LQ tank is. Something very similar is going to throw off your PH sensing to some extent, though probably not as dramatically as the ORP effects.

Changing the flow rate is going to have non-linear effects on the amount of chlorine added by the LQ, dramatically affecting the ORP reading.

This setup is also going to be affected by how dirty the filter is, because that will be changing the pressure differential that drives the LQ and thus the chlorine flow rate, which will again have non-linear effects on the amount of chlorine injected.

Net effect, using an LQ and PH/ORP automation on the same pump is problematic. If the UV is before the sensors that will also complicate things, though not by nearly as much.

Sorry for the confusion - the LQ is disconnected, I re-used the taps to circulate water through the sensor bowl on the chemlink - but the intake was after the UV light. I just moved the intake line to a point before the UV light. The chlorine and acid injections are downstream of the heaters, right before the return lines head back to the pool.

Good. That all makes complete sense now.

Sensors before the UV is the way you want to go. That way you are measuring the level in the pool (or as close as possible).

Another thing I am finding is that since I have a pretty large body of water and very low flow rates, it takes a while for Chlorine entering the pool to mix such that the concentration at the drains and skimmers represent true ORP levels.

To compensate I force a delay of 60min between 10min chlorine dosings - I learned that the hard way yesterday when I had the delay of 1min, which led to an eventual overdose.

Update:

PH is basically fool proof as long as there is acid in the tank. I think I need to increase the level to 7.5 because my alkalinity levels fall. Maybe I need to go Borax.

ORP on the other hand is interesting. I think there is a lot going on that causes the reading to vary in my pool. It goes up in the evening and down in the daytime, which is probably UV burn off and water temp. It also reads higher when we're in the pool sloshing about which tells me we probably don't have good circulation running at this low pump speed.

In general though, I've been watching the FC levels and it is usually between 1.5 and 3, with a low CYA that's not bad.

ShakenBake - you are using the exact set up that i have been looking at installing for my clients (SpectraLight UV & Chemlink). I would like to discuss your set up and experience if possible.

Regards, Tim

sent you a pm

Update:

After going to 30ppm Borax, I'm barely using any Clorox. FC levels are pretty steady between 1 and 2, with low CYA.

PH is steady at what ever I set it to. I have it set to 7.6 right now to see if that helps maintain the TA levels. It's still using a lot of acid, but I think it's due to our water feature and cooling towers/sprayers. I bought a digital PH meter with calibration liquids that I use as a way to calibrate the Chemlink's PH sensor. I calibrate the chemlink if the reading is off by 0.1.

I'm pleased that the ORP has become pretty reliable for me. I was worried based on all the negative experiences posted here.

Update: Season 2 with the C1900

Lesson #1: Pumps and tanks should not be co-located, even if you have one of those Stenner tanks with an integrated pump mount. I ended up buying a new pump, the original unit on the acid tank had too many seized/rusted parts to repair, cheaper to buy a new one. No need for an adjustable rate unit.
Action #1: Moved the pumps away from the tanks. I mounted them to the same board the probes and C1900 are mounted. Vibration from the pumps is a bit disconcerting though. BTW the new 2012 stenner pumps have a redesigned head that is easier to thread the pump tubes through, and a screw-less assembly.

Lesson #2: When the C1900 stops responding to calibration set points, it's because it's out of range. The probe is shot. Undocumented behavior.
Action #2: Got a new pH probe, though I was able to survive for a bit by adjusting my set points to compensate for the sliding pH probe. ORP sensor seems to be within what I expected based on my measurements from last year.

Lesson #3: Temperature matters. The pH probe slides a couple points across extreme temps. The C1900 is not temperature compensated
Action #3: don't pull my hair out

Lesson #4: They say not to let these things freeze. I agree. First time it touched freezing in Austin, the pump tube on the chlorine unit started leaking. Sucks....
Action #4: Pull the pumps during winter just in case it freezes. I'd like to figure out a insulated enclosure to keep the units from freezing...we virtually never see a hard freeze in Austin.

Lesson #5: Don't listen to the pool store, and the pH titration tools we have are not quite accurate enough/reliable enough to calibrate a pH probe. I found my color Q unit to be bad, as well as a batch of Phenol Red I got from the pool store.
Actions #5: Buy a good, $50 digital pH probe with temp compensation, that can be calibrated with 7 and 4 pH solutions brings sanity to your world.

Lesson #6: Saddle clamps are brittle....keep a spare or two.
Action #6: get a couple 3/8" spares.

I just installed a Chemlink C1900 on my pool, and I have a few questions.
1) Do you power the C1900 all of the time, or just when the Pump is running? I see no documentation on thin in the manual.
2) I want to use the OPR output to avtivate my Aquapure chlorine generator. It seems that the low voltage OPR output is what should be used to drive the OPR input on the Aquapure, but the manual says to connect the Chlorine generator to the high voltage output. I assume they want me to power up/down the Aquepure unit, instead of controlling it using the low voltage ORP output.
3) Did you add a power outlet that is switched by the C1900 to run the Stenner acid pump?

Anyone with input on this please let me know.

1) The C1900 requires power all the time. I put it on a separate breaker. There is a flow switch in the sensor bowl that disables it when there is no flow from the main filter pump.
2) I don't know the answer to this. JasonLion mentioned that a SWG cell generates dissolved hydrogen gas, which throws the ORP reading off while the cell is on. Something to experiment with.
3) Yes, I put an outdoor outlet that is switched by the C1900. Top plug is for ORP, bottom is for PH.

have fun