Testing for dissolved organics in a seahorse tank.

[Dan_P]

@Randy Holmes-Farley my go to for organics in the lab is TGA, can you think of a way to get the sensitivity you'd need for a reef sample at home?

When I do a back of the envelope calculation, the ratio of organic matter to sodium chloride in a seawater sample is minuscule. Even if you could convert the organic matter to CO2 and N2, which is doubtful, the TGA would not notice the weight loss, right?

 

[J1a]

I have found a live monitoring of BOD through tryptophan-like fluorescence. It costs about $1k. Probably that's the cheapest possible price for this method.

Another way is perhaps use a potassium permanganet test for COD, which will give limited insight to the amount of TOC in the water.

 

[Dan_P]

I have found a live monitoring of BOD through tryptophan-like fluorescence. It costs about $1k. Probably that's the cheapest possible price for this method.

Another way is perhaps use a potassium permanganet test for COD, which will give limited insight to the amount of TOC in the water.

The high temperature basic permanganate is a straightforward test but heating the sample above 100 C does not lend itself to home use . Maybe a 24 h digestion period at room temperature would be useful.

How are you using the fluorescence data? Trending it or using it to make maintenance decisions?

 

[rayjay]

OK, new challenge beyond having no idea what some of the replies actually mean.
For the free chlorine test, to get 1ppm of chlorine to add to the sample isn't easy for a hobbyist.
I don't have volume measuring devices other than measuring cups up to 1L which I suspect is not fine enough to get accurate dilution of bleach, but I do have scales, one measures in grams and the other in 1/100g for small measuring.
I also have syringes, 1ml, 3ml, 5ml and a large 60ml.
Would my final dilution be accurate enough if I take 5ml of 4% bleach, add it to a container and add water to total weight of 1,000g? I would then take another 5ml of the dilution and again add water to total 1,000g. The final dilution would be 1ml of this last one and again dilute to 1,000g.
If my cognitive impairment isn't too bad at the moment, I believe that should give me a litre of 1ppm bleach/chlorine.

 

[J1a]

The high temperature basic permanganate is a straightforward test but heating the sample above 100 C does not lend itself to home use . Maybe a 24 h digestion period at room temperature would be useful.

How are you using the fluorescence data? Trending it or using it to make maintenance decisions?

There is a ready made kit for PP - BoD by kyoritsu.

Search Result for : BOD - KYORITSU CHEMICAL-CHECK Lab.,Corp.

en.kyoritsu-lab.co.jp

I do not have the probe for BOD, it's not cheap. If I do get it, I would suppose I look at the trend first, perhaps even collect some water from nearby reefers to get some sense of scale, then see how to move on from there.

Interestingly, they also have a chlorophyll fluorescence measurement for cyanobacteria.

By the way, the BOD probe is not from kyoritsu.

 

[rayjay]

OK, new challenge beyond having no idea what some of the replies actually mean.
For the free chlorine test, to get 1ppm of chlorine to add to the sample isn't easy for a hobbyist.
I don't have volume measuring devices other than measuring cups up to 1L which I suspect is not fine enough to get accurate dilution of bleach, but I do have scales, one measures in grams and the other in 1/100g for small measuring.
I also have syringes, 1ml, 3ml, 5ml and a large 60ml.
Would my final dilution be accurate enough if I take 5ml of 4% bleach, add it to a container and add water to total weight of 1,000g? I would then take another 5ml of the dilution and again add water to total 1,000g. The final dilution would be 1ml of this last one and again dilute to 1,000g.
If my cognitive impairment isn't too bad at the moment, I believe that should give me a litre of 1ppm bleach/chlorine.

TRY THIS AGAIN!! I think my calculations were 1,000 too high.
5ml of a 4% bleach solution diluted to 1,000g should be now 200ppm so 5ml of that diluted solution, again diluted to 1,000g should now be down to 1ppm. (I hope)

 

[Dan_P]

TRY THIS AGAIN!! I think my calculations were 1,000 too high.
5ml of a 4% bleach solution diluted to 1,000g should be now 200ppm so 5ml of that diluted solution, again diluted to 1,000g should now be down to 1ppm. (I hope)

Yeah, 5 X 40,000 ppm / 1000 = 200 ppm and 5 mL X 200 ppm / 1000 mL = 1 ppm.

 

[rayjay]

OK, I had to rethink a lot of this as I didn't read some of Dan's info correctly. I made a chlorine 1ppm solution rather than something I could add to make the test sample 1ppm.
Testing for organic N compounds

Will need a rewrite: After a LOT of messing around and finding out how to use this kit with chlorine addition, this is what I came up with so far. I've probably done 25-30 tests already.
First I had to come up with a chlorine solution suitable to add to the samples making a 1ppm chlorine solution.
I used no name bleach that I had to search online for to get the strength as it wasn't on the bottle like most bleach bottles now.
It was just 4% strength.
As I don't have graduated cylinders and only measuring cups for fluid measure, I used a scale to weight the water.
I took a 1ml syringe to measure out 1ml and added it to a container. I then added RODI water (distilled is fine) until the total weight was 800g. This gives me a solution of 50ppm.

1.0 times 40,000 divided by 800 = 50

I'll leave out all my screwups and get to when I finally got a handle on this testing.
Using the Hanna Free Chlorine Test Kit, I added the required 5 and 3 drops of the two reagents, and then added 0.1ml of the 50ppm chlorine solution followed by filling to the 5ml mark on the test container with new salt water. This makes the chlorine concentration in the sample at 1ppm.
The colour change is immediate upon adding the chlorine and adding the sample plus gentle shaking the sample allowed a comparison that appeared to be about 1mg/L. Leaving sit for 5 minutes I saw no change in colour. I repeated using seahorse tank water and I got EXACTLY the same results. I was expecting a difference and got none.
I then used a sample of water from a small tank that only has some rock with red macro on it and the only moving livestock is miniature limpets.
EXACT SAME RESULTS!!
Now, I'm kind of ticked off figuring this is NOT going to work and I did a LOT more re-testing with no change in results.
A final test of tank water I left for 9 hours the colour change was slight but noticeable, but I don't know if it was because some chlorine was used up or instead, due to degradation of the test over the 9 hrs.
Finally, I realized that IF my water IS sufficiently controlled for quality then there might be no actual organic N compounds to absorb the chlorine to any degree.

When I woke up today I thought about another way to check things.
I thawed mysis shrimp (part of a flatpack) and collected the water from the thaw with no rinse, just the moisture that was in the pack. I figured it surly has to have DO in it and hopefully N compounds.
Sure enough, when I used a sample from the mysis water, the test withing 15 seconds went from colour to clear indicating N compounds using up the 1ppm bleach.
Next I did dilutions of the mysis water to check sensitivity. 1/2, 1/4 and 1/10.
With the 1/2, it was similar to the full strength but took maybe 30 seconds to clear the colour.
With the 1/4, it took 5 minutes to lighten the colour to go from 1.0mg/L to less than 0.5mg/L.
With the 1/10, after 5 minutes the colour changed from 1.0mg/L to 0.5mg/L
It is obvious then that the test IS able to pick up organic N compounds, but as I have NO way to know the level actually in the mysis water, I can't say that tank water that is capable of increasing the odds of seahorse bacterial disease will also have sufficient levels to be detected.
It will take a lot of testing and recording data from countless numbers of hobbyists capable of doing reasonably accurate testing.
I have pics of the tests but don't know how to put them here.

 

[rayjay]

OK, I've got the web page working. It has the above information on it but below, it has pictures of the various test results.

Testing for organic N compounds

 

[taricha]

A couple of comments suggestions on the front end. Maybe more after I give your work a close read.

1) I'd avoid no-name bleach. I bought one that I had to dig through extensive online documentation for and it only said it was somewhere between 1 and 4%. Clorox for me after that. % printed on the bottle, large company with presumably decent batch control.

2) for a sample of "good" water as a comparison, take a liter of your tank water and bubble it (airline) with a teaspoon of rinsed GAC for a few hours to a day or so. You ought to detect difference between your raw tank water and the treated tank water. It was large for my water.

3) for a sample of slightly "bad" water, and a test of sensitivity, see if you can detect the difference between tank water pre feeding and 30min post-feeding after a big meal of frozen food. Chlorine demand was able to detect this difference for me, though it was much smaller than the difference with treating via GAC.

 

[Aspect]

If you're protein skimmer has a foam head, then there are DOCs, if it is fizzing without forming a foam head then you don't have DOCs. lol

 

[taricha]

If you're protein skimmer has a foam head, then there are DOCs, if it is fizzing without forming a foam head then you don't have DOCs. lol

oh, yeah. That reminds me. Addition of 1% skimmate (0.1mL in 10mL tank water ) also gave me a marker for "bad" water that chlorine demand registered very easily.

 

[rayjay]

Thank you taricha for your comments.
For me here in Canada, the no name brand is sold by Loblaws, the biggest grocery chain and they responded immediately to my query on strength.
I also have a bottle of Clorox here @ 8.25% but it is NOT marked on the bottle here. I went to the website to get the %.
My tank water is probably cleaner than what you have as I do so many frequent large water changes due to seahorse affinity for bacterial infections. I run GAC full time on this tank as I have stopped using the skimmer.
As I'm phasing out of the hobby, all I have left is the one abdominalis seahorse and I feed a little less than a gram of mysis each feeding so I don't expect it will make a dent in the testing before or after. I'll give it a try anyway.
For seahorse keeping, just a sign of a skimmer output is not a close enough sign to know when the seahorses are going to be affected by nasty bacteria. However, as I'm no longer using any of my skimmers it's moot point. In the last decade as we realized just how clean the water needs to be for seahorses, I've never had a lot of skimmer output. Definitely nowhere near like my reef tanks.
My skimmers are all homemade, 4"dia., around 6-6.5' tall and are countercurrent air driven.

 

[rayjay]

Doing more thinking last night in bed and considering how slight the change was in the test of mysis juice at 1/10th dilution, realizing that in fact, our tank conditions are almost certainly going to be a LOT more diluted than this, rendering my testing basically unproductive for our intentions.
While this test might be sufficient to know when GAC has expired, in our seahorse tanks where we usually do FAR more extensive cleaning and water change volume and frequency in order to lessen the bacterial infections we lose so many seahorses to, I don't think it will be able to measure the low levels of organic N compounds present.

Unfortunately, the next best alternative I can find is also a Hanna test system but it’s a colorimeter checker, expensive @ $64 and needing more expensive reagent packets @ 25 for $22.

As it’s an Ultra Low Free Chlorine checker, it measures in ppb, which is 1/1000th of a ppm. However, I don't know if it is just going to give me the same results as the test kit but giving an actual figure that is 1,000 times greater. Can it actually detect, say 100-200 ppb that with the test kit I have, I cannot do?

As this is much more expensive, it’s doubtful that we could get sufficient numbers of hobbyists to obtain this, especially for an unproven test procedure.
Thoughts???

Ultra Low Range Free Chlorine Colorimeter – Checker® HC

The HI762 Free Chlorine Ultra Low Range Checker®HC (Handheld Colorimeter) provides a simple, accurate and cost-effective way to measure free chlorine at very low concentrations.

www.hannainst.com

 

[Dan_P]

Thank you taricha for your comments.
For me here in Canada, the no name brand is sold by Loblaws, the biggest grocery chain and they responded immediately to my query on strength.
I also have a bottle of Clorox here @ 8.25% but it is NOT marked on the bottle here. I went to the website to get the %.
My tank water is probably cleaner than what you have as I do so many frequent large water changes due to seahorse affinity for bacterial infections. I run GAC full time on this tank as I have stopped using the skimmer.
As I'm phasing out of the hobby, all I have left is the one abdominalis seahorse and I feed a little less than a gram of mysis each feeding so I don't expect it will make a dent in the testing before or after. I'll give it a try anyway.
For seahorse keeping, just a sign of a skimmer output is not a close enough sign to know when the seahorses are going to be affected by nasty bacteria. However, as I'm no longer using any of my skimmers it's moot point. In the last decade as we realized just how clean the water needs to be for seahorses, I've never had a lot of skimmer output. Definitely nowhere near like my reef tanks.
My skimmers are all homemade, 4"dia., around 6-6.5' tall and are countercurrent air driven.

I recently did a Triton NDOC test on my system and have 0 ppm organic nitrogen and a few ppm of organic carbon. I have a GAC reactor (1 L GAC) and wet skim, removing 2 liters of skimmate per day for a 100 gallon system. I also have a countercurrent skimmer but only 24 “ tall.

The reason preventing low organics in most aquaria is automatic water replacement. Most if not all skimmer users who have such a system under utilize their skimmer. They must throttle back waste removal to prevent dilution of their system’s salinity. I wonder if the seahorse hobby might be similarly affected.

 

[Dan_P]

Doing more thinking last night in bed and considering how slight the change was in the test of mysis juice at 1/10th dilution, realizing that in fact, our tank conditions are almost certainly going to be a LOT more diluted than this, rendering my testing basically unproductive for our intentions.
While this test might be sufficient to know when GAC has expired, in our seahorse tanks where we usually do FAR more extensive cleaning and water change volume and frequency in order to lessen the bacterial infections we lose so many seahorses to, I don't think it will be able to measure the low levels of organic N compounds present.

Unfortunately, the next best alternative I can find is also a Hanna test system but it’s a colorimeter checker, expensive @ $64 and needing more expensive reagent packets @ 25 for $22.

As it’s an Ultra Low Free Chlorine checker, it measures in ppb, which is 1/1000th of a ppm. However, I don't know if it is just going to give me the same results as the test kit but giving an actual figure that is 1,000 times greater. Can it actually detect, say 100-200 ppb that with the test kit I have, I cannot do?

As this is much more expensive, it’s doubtful that we could get sufficient numbers of hobbyists to obtain this, especially for an unproven test procedure.
Thoughts???

Ultra Low Range Free Chlorine Colorimeter – Checker® HC

The HI762 Free Chlorine Ultra Low Range Checker®HC (Handheld Colorimeter) provides a simple, accurate and cost-effective way to measure free chlorine at very low concentrations.

www.hannainst.com

Let’s revist the strength of the link between ”organics and seahorse loss”. Should I just get to work searching the internet or do you have a link?

 

[rayjay]

I recently did a Triton NDOC test on my system and have 0 ppm organic nitrogen and a few ppm of organic carbon. I have a GAC reactor (1 L GAC) and wet skim, removing 2 liters of skimmate per day for a 100 gallon system. I also have a countercurrent skimmer but only 24 “ tall.

The reason preventing low organics in most aquaria is automatic water replacement. Most if not all skimmer users who have such a system under utilize their skimmer. They must throttle back waste removal to prevent dilution of their system’s salinity. I wonder if the seahorse hobby might be similarly affected.

I think it's entirely possible Dan. How many I'm not sure but occasionally I'll find a post talking about salinity going low.
Our recommendations for skimming seahorse tanks is to get one that is rated for at least double the volume you have, but 3 or 4 times larger is much better and usually proves to be more successful for keeping DO low.
However, if someone complained to me that their skimmer was lowering their salinity in the tank then I'd be assuming their water change volume and frequency are insufficient and that eventually they will end up with bacteria problems in the seahorses. Unlike my reef tanks, I've never had occasion to up the salinity in seahorse tanks with skimming over 20 yrs but then I figure it is basically being rectified by those large frequent water changes. I top up for evap daily but on water change days I check the salinity and perhaps don't add quite as much top up to get to my target before I replace with new water at my target level.
Then too, there is the argument for using GAC if not alone then in addition to skimming as Randy commented on this thread that not all DOs are skimmable.
There are some US hobbists now experimenting with a GAC replacement called Aqua Char, using it in Robert King's Char Chamber he has donated to some hobbyists for experimenting.
I don't know the workings but am "told" it is superior to GAC and doesn't release anything when expired. I'll believe THAT when I see it.

 

[rayjay]

Well, not totally brain dead yet. I had some thoughts on measuring small concentrations.
With this experimental testing, I'm not dealing with factual numbers but dealing with colorimetric comparisons.
Also, I have an Ultra low Phosphorus checker by Hanna so I figured I don't really need to worry about scale as I'm just comparing readings I get from samples of new water, tank water and tank water if bacteria gets to seahorses.
Just to trial it, I used a cuvette from the UL kit an added reagents from the original free chlorine test kit.
These cuvettes are 10 ml rather than the 5ml sample size for the FCTK but I still used the 5 and 3 drops of reagent followed by 9.7ml of new salt water. However, I added .2ml of 50ppm chlorine so the sample still would have 1ppm chlorine. The reading I got in the Hanna Phosphorus checker was 200.
Just to see what would happen, I used a syringe to remove most of the fluid in the cuvette and added exactly 5ml more of new salt water and then replaced original test sample to the 10ml mark and took a reading I think it was 159 but forgot to write it down.
I repeated this measure again and got a third reading of 22.
Not exactly scientific as I should by rights have done the test at various measured strengths of bleach, but it was sufficient to show me that using the Ultra Low phosphorus checker will work to determine comparisons.
Now, as I write this, I wish I had removed small portions at a time, say .5ml and replaced with salt water, only SLIGHTLY diluting the sample to see if it registers those small amounts.
Maybe I'll leave that for tomorrow.

 

[Dan_P]

Well, not totally brain dead yet. I had some thoughts on measuring small concentrations.
With this experimental testing, I'm not dealing with factual numbers but dealing with colorimetric comparisons.
Also, I have an Ultra low Phosphorus checker by Hanna so I figured I don't really need to worry about scale as I'm just comparing readings I get from samples of new water, tank water and tank water if bacteria gets to seahorses.
Just to trial it, I used a cuvette from the UL kit an added reagents from the original free chlorine test kit.
These cuvettes are 10 ml rather than the 5ml sample size for the FCTK but I still used the 5 and 3 drops of reagent followed by 9.7ml of new salt water. However, I added .2ml of 50ppm chlorine so the sample still would have 1ppm chlorine. The reading I got in the Hanna Phosphorus checker was 200.
Just to see what would happen, I used a syringe to remove most of the fluid in the cuvette and added exactly 5ml more of new salt water and then replaced original test sample to the 10ml mark and took a reading I think it was 159 but forgot to write it down.
I repeated this measure again and got a third reading of 22.
Not exactly scientific as I should by rights have done the test at various measured strengths of bleach, but it was sufficient to show me that using the Ultra Low phosphorus checker will work to determine comparisons.
Now, as I write this, I wish I had removed small portions at a time, say .5ml and replaced with salt water, only SLIGHTLY diluting the sample to see if it registers those small amounts.
Maybe I'll leave that for tomorrow.

Sounds like there might be an opportunity here. @taricha and I both use the Hanna Checkers for light intensity measurements different from their intended use, for example, the silicate Checker for total ammonia measurements with the modified API ammonia test kit.

 

[rayjay]

I should learn NOT to post something until a long time after I plan to.
After much more testing, and finally re-reading the Phosphorus testing instructions, I found that the 200ppb reading is a maximum capable with this checker. So, the 200 reading I got using 1ppm chlorine was just the maximum the test could do. My mind had been set on 500ppb because that is what the Ultra Low Range Free Chlorine Checker limit is.
I've now tried with chlorine doses .9, .8, .7, .6 ppm and all still showed 200ppb. Finally, at the .5ppm chlorine strength, the readings start showing at 197ppb.
Basically then, it's doing the Hanna free chlorine test kit procedure using 1ppm chlorine added, then transferring the contents to the cuvette for the Phosphorus checker and toping up with sample water to the 10ml mark to do the test.
Now, I'm sitting here wondering what the heck complication I'm going to find next.
I never used to make so many mistakes back when I was younger!!