Phytoplankton culture water?

[Jay Hemdal Verified Community Expert]

Hi folks,

I have a general question that's been bugging me for some time now. I've grown various phytoplankton cultures for 30+ years. I use them to feed rotifer or copepod cultures for raising larval fish. Typically, I use a modified Guilliards f2 nutrient growth material.

I hear people are adding phyto cultures to their reefs now. How do you avoid adding excess nutrients and waste products from the culture water? I tried micron filtration and even centrifuge, but wasn't pleased with the results......

Thanks,

Jay

 

[Mhamilton0911]

I just recently started a phyto culture and out of curiosity I set up a test for NO4 and PO3 and found no detecable amounts. Even with a high concentration. I am using just salifert tests though. And 7 day phyto. I'm assuming the phyto used all the fertilizer in that 7 days.

I first tested plain fresh saltwater, 0 for both nitrate and phosphate. Then I added 1ml to a quart of fresh saltwater. Still 0 for both. I upped to 5ml/ quart of saltwater, still 0 for both. I again upped to 10ml phyto to 1 quart saltwater, still testing 0 nitrate and phosphate.

So by my math, at the 10ml/qt dose, that's 40ml per gallon, I have a 29g tank, I'd have to dose 1160ml to my 29g to get the same concentration, thats more than a quart of phyto into my tank, which will never happen. I feel confident adding my shotglass worth of phyto and not adding extra nutrients.


What nutrients or waste products are you worried about specifically?

 

[Jay Hemdal Verified Community Expert]

I just recently started a phyto culture and out of curiosity I set up a test for NO4 and PO3 and found no detecable amounts. Even with a high concentration. I am using just salifert tests though. And 7 day phyto. I'm assuming the phyto used all the fertilizer in that 7 days.

I first tested plain fresh saltwater, 0 for both nitrate and phosphate. Then I added 1ml to a quart of fresh saltwater. Still 0 for both. I upped to 5ml/ quart of saltwater, still 0 for both. I again upped to 10ml phyto to 1 quart saltwater, still testing 0 nitrate and phosphate.

So by my math, at the 10ml/qt dose, that's 40ml per gallon, I have a 29g tank, I'd have to dose 1160ml to my 29g to get the same concentration, thats more than a quart of phyto into my tank, which will never happen. I feel confident adding my shotglass worth of phyto and not adding extra nutrients.


What nutrients or waste products are you worried about specifically?

f2 media has a number of things I wouldn't want to add to my tank:

https://ncma.bigelow.org/PDF%20Files/NCMA%20algal%20medium%20f_2.pdf

My guess is that when people make this up for phyto culture, they drop the silica, but IDK for sure.

I'm worried because phyto cultures crash in an absence of nutrients, so if I'm adding a fresh culture, I know I must be adding some nutrients as well. In addition, technically, the phyto doesn't remove nutrients, it only sequesters it. My nutrient mixes are pretty rich. Those nutrients get bound up in the phyto cells, but they are still there in the culture.

I'm not sure I can test culture water on my spectrophotometer - the base color of the culture itself may interfere.

So here is the basic conundrum: People take great care to only use RO/DI water in their reef tank, but then go and pour in some grody phyto culture water....


Jay

Jay

 

[sixty_reefer]

Hi folks,

I have a general question that's been bugging me for some time now. I've grown various phytoplankton cultures for 30+ years. I use them to feed rotifer or copepod cultures for raising larval fish. Typically, I use a modified Guilliards f2 nutrient growth material.

I hear people are adding phyto cultures to their reefs now. How do you avoid adding excess nutrients and waste products from the culture water? I tried micron filtration and even centrifuge, but wasn't pleased with the results......

Thanks,

Jay

Hi jay, are you mainly concerned with the traces from the f2 contamination?

 

[Mhamilton0911]

I ran my test for nitrate and phosphate because that's the number one thing I gathered from many hours of reading was that dosing phyto could raise those nutrients. I actually have a starved system and could use those extra nutrients. I should be adding nitrate and phosphate to get any detecable readings, but I haven't been dosing those lately, I'm trying to get those up naturally.

 

[Jay Hemdal Verified Community Expert]

Hi jay, are you mainly concerned with the traces from the f2 contamination?

Yes, as well as the nutrients bound up in the algae cells themselves. Then, what about phenols/cresols and other waste products that can’t be measured? Algae cells are pretty “leaky” and let some materials escape….
Jay

 

[HuduVudu]

I used calcium nitrate or magnesium nitrate for a nutrient source.

 

[sixty_reefer]

Yes, as well as the nutrients bound up in the algae cells themselves. Then, what about phenols/cresols and other waste products that can’t be measured? Algae cells are pretty “leaky” and let some materials escape….
Jay

As far as getting a cleaner culture of phytoplankton there is two ways.
One is to use a product called TNC Complete aquarium plant food (it’s mainly used in freshwater) I find the formula clean and grows phytoplankton really well.
the second if the goal is to grow rotifers and copepod in large numbers I would suggest freeze dried phytoplankton, it’s more expensive although it can’t be better than that as they are produced using seawater.
In relation to demineralisation almost everything is used by organism including bacteria in aquaria and what’s not it becomes stored as detritus (carbon stored).
are you observing a issue in nutrients on your breeding tanks? As this could be one of the side effects of large phytoplankton additions

 

[Reefer Dan]

Yes, as well as the nutrients bound up in the algae cells themselves. Then, what about phenols/cresols and other waste products that can’t be measured? Algae cells are pretty “leaky” and let some materials escape….
Jay

Sorry I know this is an old thread, but Jay aren’t some of these things removed via protein skimmer and/or activated carbon? I’m curious the follow up on this perspective.

 

[Jay Hemdal Verified Community Expert]

Sorry I know this is an old thread, but Jay aren’t some of these things removed via protein skimmer and/or activated carbon? I’m curious the follow up on this perspective.

Skimming and carbon reduce nutrients, but don't remove them 100%, and the amount of actual removal is based on how well the skimmer is operating, how fresh, and how much carbon is used, etc.

I guess the basic question remained unanswered: in reef aquariums where nutrient loading is a concern, why would people add algae cultures that will just add more nutrients? I can see that no real harm would be done in nutrient poor systems, but in other systems, seems like it would be a problem.

Jay

 

[Hats_]

I have been interested in this topic too so i had someone i know eho cultures it test the N and P of the water in the cultures he is selling and the amount of nutrients was staggering! 0.2 ppm po4 and 50ppm no3...

 

[Reefer Dan]

I have been interested in this topic too so i had someone i know eho cultures it test the N and P of the water in the cultures he is selling and the amount of nutrients was staggering! 0.2 ppm po4 and 50ppm no3...

Curious, how was this tested? Phyto has a color so I imagine it could make some tests a little skewed. Also, I would assume if the phyto was live and then killed by the test (likely rupturing the cell) it would impact the test.

I would suspect that testing the clear water after the phyto has settled down to the bottom would be a little more accurate representation

 

[Jay Hemdal Verified Community Expert]

Curious, how was this tested? Phyto has a color so I imagine it could make some tests a little skewed. Also, I would assume if the phyto was live and then killed by the test (likely rupturing the cell) it would impact the test.

I would suspect that testing the clear water after the phyto has settled down to the bottom would be a little more accurate representation

Yes - dense algae cultures can cause unpredictable changes to colorimeter water tests. A fine micron filter can remove most of the algae cells before running the test.

When I was culturing micro, I was using a modified Gulliard’s nutrient solution, so I know my culture water was heavy in nutrients right from the start. Even if the nutrients get taken up into algae cells, those nutrients are still in the solution. Damping that culture water into a freed system then adds those nutrients to the water….

 

[DaJMasta]

F/2 is formulated to be used, not to stay ambient in the solution, so they're not just including things that aren't needed by the algae cells for growth. So the nutritional value of those elements becomes a portion of the nutritional value of the algae that grows in the solution, and rather than most of it being bound up in the solution when it comes time to harvest, the vast majority is in the algae cells and is consumed by the things eating it. Because the formulation is made to be what microalgaes generally require, these same nutrients would be present in wild microalgaes, and would similarly be eating by the things preying on them, so in my understanding, the things that eat phytoplankton either needs these compounds or have a mechanism with dealing with the excess.

I don't have the tools to measure it nor the chemistry expertise to 'do the math', but that's at least the intention, right? Skimming, algae scrubbing, and some water changes can take up most of the slack of an imperfect balance of nutrients, some still being present in the solution, or other minor pitfalls. As it stands, I've been dosing a fairly large amount of dense phytoplankton culture to my tank daily and have yet to see any ICP evidence of a buildup of unwanted compounds, I just see an increase in phosphate levels in the water (which isn't ridiculous and isn't all that harmful.)

As for what the algae is fed to, I do sieve my copepod cultures before feeding, so that the culture water added to the tank is probably about 5% of the culture water removed from the culturing vessels (which would include any buildup from phytoplankton cultures dosed directly to them as food.) The total daily volume into the tank is much lower, and I still have yet to see issues with long term build up in the tank or even in the culture vessels (some of which have been producing for nearly a year before being reset.)

 

[Jay Hemdal Verified Community Expert]

F/2 is formulated to be used, not to stay ambient in the solution, so they're not just including things that aren't needed by the algae cells for growth. So the nutritional value of those elements becomes a portion of the nutritional value of the algae that grows in the solution, and rather than most of it being bound up in the solution when it comes time to harvest, the vast majority is in the algae cells and is consumed by the things eating it. Because the formulation is made to be what microalgaes generally require, these same nutrients would be present in wild microalgaes, and would similarly be eating by the things preying on them, so in my understanding, the things that eat phytoplankton either needs these compounds or have a mechanism with dealing with the excess.

I don't have the tools to measure it nor the chemistry expertise to 'do the math', but that's at least the intention, right? Skimming, algae scrubbing, and some water changes can take up most of the slack of an imperfect balance of nutrients, some still being present in the solution, or other minor pitfalls. As it stands, I've been dosing a fairly large amount of dense phytoplankton culture to my tank daily and have yet to see any ICP evidence of a buildup of unwanted compounds, I just see an increase in phosphate levels in the water (which isn't ridiculous and isn't all that harmful.)

As for what the algae is fed to, I do sieve my copepod cultures before feeding, so that the culture water added to the tank is probably about 5% of the culture water removed from the culturing vessels (which would include any buildup from phytoplankton cultures dosed directly to them as food.) The total daily volume into the tank is much lower, and I still have yet to see issues with long term build up in the tank or even in the culture vessels (some of which have been producing for nearly a year before being reset.)

But the nutrients are just sequestered - in the algae or free in solution, they are still there. The only exception would be something that off gasses.

There is still the total nutrient import into the system. People battling nutrients but then adding algae culture water are just exacerbating the problem.

 

[DaJMasta]

I'd agree - I guess the problem then only lies in your intent.

If you're feeding phyto to feed the organisms in the tank, it should work out exactly as intended. If you're feeding phyto because of the sometimes purported benefit of somehow lowering nutrients (and as you've said you add it, and it doesn't generally stay in suspension sufficiently to multiply in any capacity to uptake nutrients already in the system), then it's snake oil and it always has been.

Adding food organisms to your tank is adding food like any other. Adding phyto, copepods, or even organically available carbon sources doesn't lower nutrients in your tank, but it does skew the balance of where those nutrients are towards being in your livestock rather than your water column.

 

[Hats_]

Curious, how was this tested? Phyto has a color so I imagine it could make some tests a little skewed. Also, I would assume if the phyto was live and then killed by the test (likely rupturing the cell) it would impact the test.

I would suspect that testing the clear water after the phyto has settled down to the bottom would be a little more accurate representation

used one of those micron filters u get with some ICP tests after letting the algae settle to collect only water. also tested using hanna which does a baseline test to compare to anyway

 

[GARRIGA]

But the nutrients are just sequestered - in the algae or free in solution, they are still there. The only exception would be something that off gasses.

There is still the total nutrient import into the system. People battling nutrients but then adding algae culture water are just exacerbating the problem.

Aren’t all nutrients not sequestered by the next food item in the chain? Algae feed other organisms that might feed other organisms yet each will contribute its own waste however much gained will be sequestered until death or consumption by another. If I’m understanding your point and that F2 that will be added to the tank might feed the coral’s own symbiotic algae but I’m not sure on latter. Just makes sense all algae or lower life forms might require similar nutrients.

 

[Hats_]

Aren’t all nutrients not sequestered by the next food item in the chain? Algae feed other organisms that might feed other organisms yet each will contribute its own waste however much gained will be sequestered until death or consumption by another. If I’m understanding your point and that F2 that will be added to the tank might feed the coral’s own symbiotic algae but I’m not sure on latter. Just makes sense all algae or lower life forms might require similar nutrients.

I think the point Jay is trying to make is that people get advised to add phyto in a variety of different circumstances and that due to the nature of how it is cultured, this may worsen problems in certain cases where people are battling nutrient imbalances.

In my case for example if I have a nano tank and I buy this phyto that I tested I might cause a major nutrient spike in my system, since there is no consensus on how much to dose per x amount of tank volume, hell i have seen people dunk entire bottles in their systems of the stuff.

Also, literature tells us that barely any coral use the most common phyto (nannochloropsis) you can buy other than some gorgonians and filter feeders, so you may just be polluting the tank with no real benefit

 

[BanZI29]

I currently culture 6 types of Phyto and this is what I have learned.
When you start a culture, you add the fert. as food for the phyto along with light. As the Phyto grows and multiplies, the fert is consumed by the phyto. Even with thalas, since you have to add silica for them to grow, they utilize that to grow and multiply. when the culture is ready, there will not be any real detectable amounts (if any at all) in the water since the phyto has used it thus, it will not go into your tank. Remember that Phyto is essentially a plant so, the main waste product of phyto will be O2, oxygen.
Also, any Nitrate or phos that is present in the phyto water, will be consumed by the phyto at some level.