Xepta AutoBalance reagent

[Dennis Cartier]

I dicided to give the DIY reagent a go tonight by measuring by weight rather than using measuring cylinders.

I also decided to mix it on a large scale but still following the ratio given above.

5 litres of 0.1N mixed with 16.2 litres of Rodi water. Totalling 21.2 litres of reagent. Unfortunately I think the ratio given above isn't completely accurate for larger scale batches.

Xepta reagent test: 8.00dkh
Diy reagent test: 8.99dkh

Hmm, so the DIY was too weak as compared to OEM with the batch you made. The larger volumes you are using will more easily show discrepancies in the ratio, than the smaller batch the previous poster was using. Measurement errors can swing the results more easily, both positively and negatively, when the volumes being measured and mixed are small.

A 1:3 ratio would be closer to matching based on your results.

 

[adz-94]

Hmm, so the DIY was too weak as compared to OEM with the batch you made. The larger volumes you are using will more easily show discrepancies in the ratio, than the smaller batch the previous poster was using. Measurement errors can swing the results more easily, both positively and negatively, when the volumes being measured and mixed are small.

A 1:3 ratio would be closer to matching based on your results.

I'll order some more 0.1n and adjust it to be at a 1:3 ratio and see what results I get.

The discrepancies with the measuring cylinders and smaller batches is the reason I decided to measure by weight rather than volume, during measuring I was able to measure out exactly 5000g of 0.1n and 16200.4g of Rodi.

 

[Randy Holmes-Farley]

I'll order some more 0.1n and adjust it to be at a 1:3 ratio and see what results I get.

The discrepancies with the measuring cylinders and smaller batches is the reason I decided to measure by weight rather than volume, during measuring I was able to measure out exactly 5000g of 0.1n and 16200.4g of Rodi.

I doubt you need high accuracy, nor do I know how you converted mass to volume, but note that 16200.4 grams of pure water at 25 deg C occupies a volume of 16,249 mL.

 

[Dennis Cartier]

Also please remember to re-calibrate the unit to prevent accumulating error that gets attributed to the reagent mixing ratio. I expect the Xepta hardware offers pH probe and volume calibrations. Getting those calibrated before evaluating the result of the DIY reagent will be very important.

 

[adz-94]

Ok so I had some more 0.1n delivered earlier this week and had another play about with the mixture tonight.

I started out with my previous mixture of 5000g of 0.1n to 16200g of Rodi this gave me a test result of 8.99dkh which was approximately 1dkh higher than the xepta reagent.

I added an additional 200g of 0.1n to the mixture and tested again this time it came back as 8.67dkh so approximately 0.7 dkh higher than the xepta.

So I slowly started adding more 0.1n to the total mixture and giving it a good mix around refilling, purging and testing until the results came down to 8.43dkh

At this point I decided to run a handful of tests back to back just to make sure the test was repeatable and results were within margin of error of each other and they were all within 0.1dkh

My tank is a DD900 reef pro with roughly 250L volume after accounting for rocks, sand, equipment etc. I aim to keep my dkh at 8.0 and right before it starting playing and running multiple test tonight my alk was 7.97dkh.

Just to be sure I reconnected the xepta reagent and that also gave me a results of 8.45dkh. So I'm guessing this upward trend is because of the amount of reagent I dumped back into my tank in a short period of time raising the alkalinity slightly each test.

So the final results for my testing were;
Xepta reagent: 8.45dkh
Diy reagent: 8.43dkh

Diy recipe :
5500g of 0.1n HCl
16200g of RODI

This gives a ratio of pretty much exactly 25:75

I doubt you need high accuracy, nor do I know how you converted mass to volume, but note that 16200.4 grams of pure water at 25 deg C occupies a volume of 16,249 mL.

Hi randy, just to address this 1000ml of 0.1n HCl is only 8.33ml of concentrated HCl and the rest is Rodi water. Giving the small amount of HCl and the accuracy that we need for making this reagent it's safe to assume both the 0.1n and Rodi used for mixing weigh the same and occupy the same volume as eachother. Just to be sure of this I was measuring out the weights of each liquid into a measuring cylinder and comparing the weigh to volume. I have attached a photo I took of 120g of 0.1n measuring exactly 120ml in the measuring cylinder.