ORP controller with dosing pump.

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JasonBigCountry

Member
Jun 21, 2022
23
Abilene, Texas
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
This looks really cool - I know this is an old post, but I was glad to see it.
I was searching for info on a very similar product they sell called the BL101 - same idea, but measures ORP (kind of a proxy indicator of Free Chlorine, but not exactly. Read Understanding ORP Measurements for Chlorine in Pools | Atlas Scientific for a more detailed explanation if you need it) and injects chlorine.

Looks nice, and your favorable write up of the BL100 has me seriously considering it.
 
Following up on this topic.
I went ahead and bought the Hanna BL101 (link above in my previous post) toward the end of last year's swimming season.
Since it was the end of the season, I just stored it until "next year" (this year). I also bought some of the other goodies I needed/wanted in order to install it. Some Flexible PVC to replace the plastic tubing connecting my AG pool to the equipment. Partly because I had a feeling the tubing was restricting flow, and partly because it was prone to collapsing (the suction side) when some restriction made it into the vacuum, or the strainer. I also installed some ball valves.

Installation of everything was fairly smooth as part of the pool opening, and after a bit of time dialing in the Hanna, I was pretty happy with the result.

Here's a quote from a mail I sent Hanna (why was I sending them mail? We'll get to that :p)

I've recently installed the BL101 that I purchased last year (I installed it as part of re-opening my pool), and after a few days to a week of tweaking and fiddling, I got it to where I felt it was running fairly well. Aside from ensuring the tank has chlorine in it for the BL101 to draw from, it's largely "set it and forget it", which is what I was hoping for. My installation consists of a five gallon tank (kind of a 'carboy' style jug) that I have sitting at ground level, the BL101 sitting at about 3.5 - 4 feet above ground, mounted to a pole with a little roof over it to shelter it from afternoon sun and any rain. All the equipment is outside. The injector and the sensor are installed in the return line from machinery to the pool (between the sand filter and the pool to be more precise). I'm using the parts that came with the BL101: the strainer/filter block in the intake jug, the soft 1/4 tubing from the intake jug to the pump, the firm 1/4 tubing from the pump to the injector fitting. The injector fitting and sensor are installed in the provided saddles on the return line. (Sensor about 2 inches in 'front' of the injector - i.e., the water flows past the sensor, and then past the injector.) Both tubing runs are in the 6-8 foot range - the suction-side is probably a bit longer than the pressure side. I leave the pool pump on all the time, as well as the BL101, except brief moments while putting the pool vac in the pool, and things like that. I leave the set point at 685, and it usually maintains a level between 670 and 715 (I see fluctuations which relate to time of day, and I think they're just a result of the changing water temperature, so I'm not too concerned about that).
Click to expand...

So, I wrote them that, and more, because there was a fly in the ointment - I noted that at about that time (six weeks after install, early in the season, so going easy on the chlorine consumption), it started having a problem with "losing it's prime". I wrote to Hanna, explained all my observations and trouble-shooting. They sent me a couple of feebies to see if they addressed the issue: a replacement injector, and a pump tubing kit (two pump tubes, some silicone lubricant). I put on one of the new tubes the very next time I saw an issue, and everything went back to running well.
Still not totally sure if the loss of prime is because the tubing is worn out, or if it's because of excessive out-gassing of the chlorine now that it's getting properly sunny and hot here (>100ºF is normal). The new tubing DOES seem to make it run like clockwork for a time.

So... The bits they sent me were free/goodwill, since I'd just bought it, but normally, that kit with the two tubes is $40-$50. Since they only seem to last 2-6 weeks totally trouble free (based on my limited experience so far), I'm not happy with that cost.

I've spent a bit of time researching tubing. Hanna's is marked VERDERPRENE which I've found online, but not for sale in quantities that I'm keen to buy. Also, it doesn't last long. :rolleyes:
I've tried some Tygon 2375 (Ultra Chemical Resistant Tubing), but it's either too big or too stiff. It is slightly bigger (~1/64") but I think this is the closest size match I could get. The real issue is probably the stiffness. Either way, the stepper motor in the pump can't handle it - it just loses steps.
I see that Stenner pumps use Santoprene. Well, some do anyway - I'm really not sure if that's the right material for a chlorine dosing pump. I also see that Stenner's replacement bits are cheaper. :)rolleyes:, again).

I think part of the issue is that the Hanna pumphead is quite small. The tubing is only 4" long, and I'd guess the radius is about 1". I think with each interval of material pumped being so small, it has a hard time with bubble build up when there's any back pressure. It appears the Stenner pumpheads (some at least) are quite a bit larger.

Right now, I'm looking at:
  1. Further alternatives for tubing at reasonable prices
  2. Possibly rigging up a Stenner pumphead with a stepper and driver that is wired into the Hanna's control system (seems doable, but quite a bit of tinkering)
  3. Possibly switching to a Stenner pump - But I'm not aware of a control system for a Stenner that's based on ORP. They all appear to be either "set the speed and walk away", or perhaps "program the speed profiles and timer and walk away" - I'm not seeing any sort of "closed loop" system, such as Hanna.
Anyway, just wanted to post the followup in case any others were interested, or stumbled on this while surfing the web. Happy to hear ideas as well. (Yes, I'm also considering SWG, but it's lower down on my list of ideas... I'm put off because I'm worried my 'non-saltwater rated' AG pool may not deal with the salt very well.)
 
I have to comment that my experience is completely opposite. I've had my BL101 dosing acid since late 2020 with very few issues.

The peristaltic pump uses tubes and rollers that are wear items as indicated by Hanna. I replace mine yearly and add a drop of silicone to the tube. Mine has never stopped working, only takes longer to get to setpoint and I can see the tube is a little worn out/crushed/stretched so I replace.

I think your issue might be that your container is well below your pump causing it to lose prime when off and cause it to work harder to try and suck the chemicals up the tube. I suggest raising your tank to as close to level (or even above) the pump and see what happens. It is a small pump with small tubing and is probably having difficulty.

New Acid Pump/Ph Controller

My pool has in-floor cleaning, SWG and a Solaxx acid dosing system, so it is as close to "maintenance free" as one can get. Untill...my Solaxx acid pump and controller started to go haywire. The peristaltic tube wore out, rollers got weak and the duckbill valve started to leak. Well...Solaxx...
www.troublefreepool.com www.troublefreepool.com

.
 
I'll give that idea a shot. I installed it low to be sure that it could never free-flow (though I suppose that may be hard to be certain of anyway).

But aren't you pumping acid, not chlorine? Does it out-gas the same way? Mine frequnently has bubbles that get into the suction line. Does that happen with yours?

Either way, an easy fix to try raising the tank. I'll give it a shot.

Thanks!
 
JasonBigCountry said:
I'll give that idea a shot. I installed it low to be sure that it could never free-flow (though I suppose that may be hard to be certain of anyway).

But aren't you pumping acid, not chlorine? Does it out-gas the same way? Mine frequnently has bubbles that get into the suction line. Does that happen with yours?

Either way, an easy fix to try raising the tank. I'll give it a shot.

Thanks!
Click to expand...
I am pumping acid, but I never get any bubbles in the line.

The good thing about this pump is that its design, makes it a defacto type of check valve with the roller squeezing the tube closed... so there might be a leak before the pump.

let us know how it goes...
 
Yeah, that's a possibility (a leak in suction) but my money is on what Hanna told me; the chlorine tends to outgas naturally.
I just pulled these up while thinking about this, which educated me a bit further:
The first three indicate the gas released is oxygen. Most interesting, that final link; the one that seems the most well-researched, doesn't appear to even mention oxygen. Instead, it mentions that the outgassing is of nitrogen trichloride, which in turn is also broken down by sunlight (but into "what" I couldn't quickly spot). Again, I didn't read the whole thing, just did some searching and spot reading. I may come back to it since it does look interesting.

What I took away from all that is that the sunlight may be REALLY aggravating the problem.

I was already trying to shade the chlorine in the tank because I knew from this site that:
  • Sunlight breaks down chlorine (I just didn't know it made bubbles while doing so)
  • Chlorine's half-life drops with increasing storage temperatures
I had a long-term loosey-goosey plan to build a little shed-let for this stuff (keep it well shaded, but provide air circulation, as well as provide shelter for local black widows and scorpions. Bonus!), once I was satisfied it would be worth the effort. Now I'm thinking I may need to do that sooner, or I'll never see the evidence I'm looking for.

Similarly, I could probably benefit from shortening the lines (esp the suction line). Again, I was holding off until I'd 'finalized' my installation plan.

Here are some photos after moving and elevating the tank.

This first shows the BL101, and the tank propped up on a few concrete blocks. Note the ORP is low (666 vs setpoint of 685) - I cleared a lost prime again just before taking this photo. The excess tubing on the ground is the suction side of the BL101. The tank was sitting by the pool before this move, so the length wasn't so excessive. Don't envy my high-tech shade devices. ;-) Yes, that's a laundry basket and a drip pan for a rabbit cage.

PXL_20230620_162117848.jpg

Side view of the storage tank. Exciting stuff!

PXL_20230620_162132539.jpg

Here you can see all the equipment - the red gizmo in sticking out of the return line from the spider valve is the ORP sensor. Just next to it is the injection valve for the chlorine (i.e. the output from the BL101).

PXL_20230620_162144316.jpg
 
Shorten the tubing

Also, is a cap loose to let air in the jug? It can't be sealed tight, air has to replace the chlorine being pumped out.
 
RLP said:
Shorten the tubing

Also, is a cap loose to let air in the jug? It can't be sealed tight, air has to replace the chlorine being pumped out.
Click to expand...
Just shortened it (suction side) by about 3.5 ft a couple hours ago, gonna go back out to see it it helped. It was struggling to pump chlorine as I walked away. :(

The cap on the tank is usually left loose, and further, the hole where the tubing exits is also not air-tight. It never sucks air when I open it up.

I'm afraid it's probably new tubing time again... I ordered two sizes of Santoprene 64A to try out. (3/16x5/16, and some probably-too-large 1/4x3/8).

I can try lifting the tank higher still, but I think the back pressure on the pressure side is way more significant.

I'm gonna laugh at myself if I end up using this as an excuse to buy a 3d printer so that I can make a custom peristaltic pump. :) (shh. Don't tell my wife). Thing is, I've seen the videos of the Stenners, and there's no way I'm gonna build a better housing than that without making it my own business to do so (and maybe not even then - they look bombproof!)
 
Just before going to bed last night I checked it again, saw the level was still too low. Since the lines did NOT appear to be full of bubbles, I decided to pull the injection valve and check to see if the Hanna could push solution through. It couldn't. I removed it and attached the spare, and it could push solution. Installed that new valve and took the old inside to try to clean it up/rinse it out. It didn't appear caked up or clogged, but after some hot water and working it, I can move the runner sleeve about now. I couldn't at first, it was well and truly 'stuck'.

This morning, it was sitting at just barely above the target (687 vs 685), so, basically, spot on.

Wondering now if this has been the real issue all along - I did rinse it a bit when I first changed the tube a few weeks back, and maybe that was part of the fix, and I just didn't realize it. I could be that a fresh tube can build a bit more pressure that a not-so-fresh tube, but that a not-so-fresh tube would be fine if the injector valve is in good shape.

FYI, when the line is full of gas near the pump, what happens is the pump tries to push the though, but the gas compresses, and then it basically 'squishes' back past the one of the compression points in the pump tubing - you can hear it, as well as see highly aerated fluid in the tube. When the tube is full of liquid, it doesn't really do that (the liquid doesn't really compress well, and the tube on the output side is fairly stiff, so shouldn't stretch too much.) Since this time I was seeing that it wasn't building ORP level (and chlorine level in the tank didn't appear to have moved much or at all) despite the pump running fast with no gas in the line, it gave me a clue that there much be a hard blockage, not just a restriction. This is what lead me to check the injector valve.

Not sure why the valve is caking up. I saw a bit of white scale on the valve. More a few weeks back, just a bit last night. Not sure if that's a salt as a result of the chemical reaction related to the outgassing, or if it's calcium. Our water is fairly hard here, and I dilute the chlorine when I add it to the tank to try to reduce the rate at which it is degraded by heat and sunlight (my understanding is that higher concentrations degrade faster). Maybe I'll just add some straight chlorine for a few weeks, and see how that goes.
 

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JasonBigCountry said:
Just before going to bed last night I checked it again, saw the level was still too low. Since the lines did NOT appear to be full of bubbles, I decided to pull the injection valve and check to see if the Hanna could push solution through. It couldn't. I removed it and attached the spare, and it could push solution. Installed that new valve and took the old inside to try to clean it up/rinse it out. It didn't appear caked up or clogged, but after some hot water and working it, I can move the runner sleeve about now. I couldn't at first, it was well and truly 'stuck'.

This morning, it was sitting at just barely above the target (687 vs 685), so, basically, spot on.

Wondering now if this has been the real issue all along - I did rinse it a bit when I first changed the tube a few weeks back, and maybe that was part of the fix, and I just didn't realize it. I could be that a fresh tube can build a bit more pressure that a not-so-fresh tube, but that a not-so-fresh tube would be fine if the injector valve is in good shape.

FYI, when the line is full of gas near the pump, what happens is the pump tries to push the though, but the gas compresses, and then it basically 'squishes' back past the one of the compression points in the pump tubing - you can hear it, as well as see highly aerated fluid in the tube. When the tube is full of liquid, it doesn't really do that (the liquid doesn't really compress well, and the tube on the output side is fairly stiff, so shouldn't stretch too much.) Since this time I was seeing that it wasn't building ORP level (and chlorine level in the tank didn't appear to have moved much or at all) despite the pump running fast with no gas in the line, it gave me a clue that there much be a hard blockage, not just a restriction. This is what lead me to check the injector valve.

Not sure why the valve is caking up. I saw a bit of white scale on the valve. More a few weeks back, just a bit last night. Not sure if that's a salt as a result of the chemical reaction related to the outgassing, or if it's calcium. Our water is fairly hard here, and I dilute the chlorine when I add it to the tank to try to reduce the rate at which it is degraded by heat and sunlight (my understanding is that higher concentrations degrade faster). Maybe I'll just add some straight chlorine for a few weeks, and see how that goes.
Click to expand...
If it is the sunlight on the Chlorine tubing you could wrap some white or black wire loom around the tubing run and try that to keep the direct sun off the tubing...
 
nofears said:
If it is the sunlight on the Chlorine tubing you could wrap some white or black wire loom around the tubing run and try that to keep the direct sun off the tubing...
Click to expand...
That's a good idea, thanks.

I ran into issues again today, and after seeing yet another attempt at 'brand x' tubing didn't work quite right, I checked the new valve, and saw it was not flowing. This led me to re-install the original (which I'd cleaned up after installing the second valve), and seeing it wasn't flowing either.

I took both valves inside, worked the rubber 'sleeve' up over the plastic body so that I could directly see the outlet ports in the body, and lo and behold, both the old and the new were packed up with what appeared to be salt. I clean both out with a un-bent paper clip and a jet of warm/hot water until they flowed freely again and appeared completely clean. I reinstalled the original after that process, and it's flowing well again, even with the older, well-worn, pump tubing.

I'm gonna drop a mail to Hanna describing this to see what they have to say. I feel like this system couldn't possibly be reliable enough to sell based on my experience, so there's probably something unique to my experience that's causing this problem. My current suspicion is that the sun is the issue, so I'll have to go ahead and properly shelter it as intended, and the loom idea sounds like a good one to cover any tubing that doesn't end up inside the enclosure (if any).
 
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