Small-scale CYA Reducer Trial

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Aqua Lab Rat

Aqua Lab Rat

In The Industry
May 1, 2015
124
Anoka, MN
Figured I'd better start a separate thread with my data. First, information about my test configuration:

Tank Equipment:

250 gallon cubicle IBC tank (plastic bulk tank w/ metal cage, sometimes called a pallet tank) with rectangular opening cut into the top. A plastic flap is used as a loose cover to reduce evaporation.
Plumbing connections run through the opening on top of the tank.
Coates 1.5 ILS electric heater (1.5KW)
Little Giant 3-MD-SC pump (11 gpm)
Filtered by an Intex type A filter. The plumbing to the pump intake connects to a 1.5" bushing jammed into one end of the filter, the other end is plugged with 1.5" threaded plug (don't knock it, it works very well for a simple test rig).

Test Equipment:
Sartorius precision balance (for weighing the CYA Reducer product)
Hach DR820 Colorimeter with DPD Test 'N Tube reagents
Oakton pH2 EcoTestr
Taylor K-2006 kit

Conditions:

The test is being run indoors with artificial lighting. It has been rainy here anyway.
Water temperature is maintained at 80 degrees F.
TA = 110, CH = 175 (approximate values, not closely monitored)
I wanted the starting CYA to be less than 100 so no dilution would be required.
All CYA measurements are taken in the same position directly below a fluorescent bench light.

Dosage:
Product bag says one 226 gram (8 oz) bag per 25k gallons, so divided by 100 for my tank size = 2.26 grams. I don't have a skimmer & forgot to premix with water - I just dumped it in near the filter.

Data so far:

Date Time Total CL Free CL pH CYA
5/6 1:10 pm 3.20 2.86 7.5 95
5/7 12:57 pm 3.05 2.72 7.5 95
5/8 1:11 pm 3.01 2.59 7.6 95
5/11 1:19 pm 2.63 2.16 7.9 95 Added 14 grams of GLB pH Down after testing
5/12 12:49 pm 2.65 2.16 7.6 95
5/13 2:53 pm 2.31 2.03 7.7 90
5/14 1:49 pm 2.31 1.93 7.8 80

I will still be running the test into next week, so we'll see if something is really happening. If it is, my guess is that it just took a while for the microbes to grow & have a visible effect. But I dislike the disappearing dot test because I wonder if I'm imagining that I see the dot, or if I went slightly too far. Will have to see a bigger change to reassure me that it isn't just user error.
:paddle:
 
If most people loose CYA over the winter when the pool is closed, with a cover, the water is cold, and after the FC is 0, then why wouldn't one mimic these conditions with minimal lighting when testing to see if BioActive works? I've wondered this since seeing all these threads testing its effectiveness. I know these may not be ideal conditions when trying to lower CYA in an open pool but maybe it would be useful when closing the pool.
 
I think the question answers itself, if CYA gets eaten over the winter without product, then there is no need to test product effectiveness under those conditions. it's when the CYA didnt get eaten over the winter that you will discover you want to reduce it - and then the test conditions are a very good approximation of the real use of the product.

my concern is the FC levels that the product requires. if you have a high CYA level, then the max allowable FC levels are always going to be algae growing conditions - which is a bummer for the product and something I would prefer they make very clear. " you will have to go green to get rid of the CYA " aint great marketing, but it's the only way I see this working out in the world.

As to the CYA levels, assuming microbial action it should be something of a exponential curve so hopefully you will start seeing a marked increase in the rate of CYA consumption.

Thanks for taking on this project
Cardano.
 
Last edited:
Patrick_B said:
Thank you for sharing your Data with us. Much appreciated. :goodjob:

I only ask out of sheer curiosity, but what else do you normally run with your 820?
Click to expand...

I mainly use the DR 820 for DPD free and total measurements. I have also used it to measure iron. The main reasons I got it were precision, portability (compared to a large spectrophotometer) and the ability to use Hach's Test 'N Tubes for the DPD. The reagent in the tubes is good up to 5.5ppm. It is so easy compared to what I was doing before, which was using their little foil packets of reagent which are limited to 2.2ppm and which I ended up either spilling powder or having trouble opening.

Hach does have a CYA reagent that I could use with the DR 820, but it is limited to 55ppm.
 
Today's data 5/15 at 1:22 pm:

TCL = 2.22, FCL = 1.82, pH = 7.9, CYA = 85. Added 14g pH Down after measuring.

Less decisive than I'd hoped. I guess we'll see what it is on Monday. Also starting to wonder if algaecides or metals might kill the microbes in some of the pool tests.
 
smackdab said:
If most people loose CYA over the winter when the pool is closed, with a cover, the water is cold, and after the FC is 0, then why wouldn't one mimic these conditions with minimal lighting when testing to see if BioActive works? I've wondered this since seeing all these threads testing its effectiveness. I know these may not be ideal conditions when trying to lower CYA in an open pool but maybe it would be useful when closing the pool.
Click to expand...

I've made that same suggestion elsewhere, at least for having a very low or zero FC just to see if the product will work at all. The main reasons that the manufacturer requires an FC level is to "brake" the reaction so that it doesn't keep going getting rid of all the CYA, also to prevent too much algae growth, and also the EPA may have restrictions about saying to lower the FC to zero (though that is exactly what happens when using some metal sequestrant products such as ascorbic acid, though the product itself lowers the FC rather than instructions having the user do so themselves before adding product).

There would be no point in using a lower temperature. The temperature should be where the bacteria and their enzymes are most effective and that's more likely to be in warm water. As for sunlight, that may not matter unless the bacteria are adversely affected by the UV in sunlight (these bacteria do not need sunlight to grow).

Ironically, if the phosphate level was very low, then that could inhibit the bacteria growth and it's not clear whether the enzyme processes in the bacteria would proceed well without such growth or at a low phosphate level. If this product worked mostly by just having the enzymes exposed to CYA, then phosphate levels shouldn't matter, but if it depends on bacterial metabolism, then phosphate levels may be important. I know that with my own experience of disappearing CYA over just a few days described in the thread It Can Happen to Anyone - Zero Chlorine, CYA-->Ammonia, that my phosphate levels were quite high at 3000+ ppb.
 
Aqua Lab Rat said:
Also starting to wonder if algaecides or metals might kill the microbes in some of the pool tests.
Click to expand...

The manufacturer has said not to use algaecides precisely for that reason. Having algaecides or 50 ppm Borates or copper/silver or chlorine may all negatively affect the bacteria. As I noted in the post above, a low phosphate level might also slow down the bacterial metabolism. Unfortunately, the manufacturer hasn't been specific about this and has only generally said not to have the FC be too high and not to use any algaecides.
 
ya the enzymes need at least 65 degrees to work best.

The few that have tested this, none have had algae problems except one poster who said his water started turning green.

and the guy from Bio-Active did say that anything else added could cause problems including algecides like polyquat.
 
Aqua Lab Rat said:
I mainly use the DR 820 for DPD free and total measurements. I have also used it to measure iron. The main reasons I got it were precision, portability (compared to a large spectrophotometer) and the ability to use Hach's Test 'N Tubes for the DPD. The reagent in the tubes is good up to 5.5ppm. It is so easy compared to what I was doing before, which was using their little foil packets of reagent which are limited to 2.2ppm and which I ended up either spilling powder or having trouble opening.

Hach does have a CYA reagent that I could use with the DR 820, but it is limited to 55ppm.
Click to expand...

I'm aware of that one, and have thought of trying it for comparison. It would do fine for a split to read up to 110 I'm sure. I still carry an 890 and it does well. When it goes, I'll upgrade, but for now it's still an excellent machine. Love the foil pillows for some of my drop testing too. The 460 DPD pillows translate directly to the Taylor 870 powder. Anyway, thank you for updating us on your Cya trial. Look forward to more results....
 

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Today (Monday) 5/18 readings:

TCL = 2.00, FCL = 1.59, pH = 7.8, CYA = 80

Today would be day 12. I plan to keep taking readings for the rest of this week so that I am well beyond the manufacturer's 10 day period.

To summarize, the first week saw no change in CYA, days 7 and 8 showed a slight drop, and now we are pretty much flat. I may re-run the test next week with a higher initial CYA value.
 
Although I can stand having zero chlorine, the next test will have chlorine levels comparable to the first one for other reasons. If I do a 3rd test it can be done at zero ppm. This time I'll start with it just under 3 ppm and let it drift down. I'll work to keep the pH between 7.0 and 7.5, though I do tend to get lazy / loose with pH control sometimes. :sleep:
 
Argh. I had hoped to start the next test run by now, but got in too much of a hurry. As a result, I'm now paying penance by having to aerate the pH up to where it should be. :sad:

It only takes a moment destroy something (including pool chemistry), but construction is always a process.
 
Test run #2 started this morning (Friday). Measurements before adding product:

Total CL = 2.60
Free CL = 2.06
pH = 7.2
CYA = 170
TA = 100
CH = 140
Temp = 79.7

Added 2.55g of Bio-Active product as follows:

Dosage determined as (250 gal. / 25k gal) x 225 grams x (170ppm / 150ppm)
Note that bag says 1 bag per 25k gallons or per 150 ppm of CYA.

Product was pre-mixed with 250mL of tap water before pouring in near my filter.

Next measurement will be Monday.
 

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