Refugium and the risk of reducing nitrates too much

[Dan Reef]

Hello,

I was reading the links below trying to find a solution for my tank:

https://www.reef2reef.com/threads/new-tank-when-to-add-marine-pure-block.354780/page-2

http://www.reefedition.com/nitrate-in-the-reef-aquarium/

https://web.archive.org/web/2004072...482/Kaneohe Bay algae N-P Larned Mar Biol.pdf

https://www.reef2reef.com/threads/refugiums-really-do-work-but-can-they-work-too-well.298305/page-4

http://reefkeeping.com/issues/2005-12/rhf/index.php

So I set up my tank for the Triton method but still didn’t send water for analysis because I live in Brazil and I’m waiting the local distributor to have test kits.

However I followed the method by using the correct sump with a modification: before the last chamber there’s a space with Marine Pure balls and some bioballs.

For the first 5 month I decided not to have any algae in the refugium and not add any additive as this was how my old tank was been managed.

Once all the corals and fishes was doing fine I decided to take the next step and added chaetomorph and 1 month after started dosing triton core7. 20 days after, problems started:

- LPS and soft not so inflated as before
- acroporas turning pale
- mileepora, specifically, not extending polyps

Fast forward 3 month and I still wasn’t able to figure out the issue. GHA took place on sand bed..

While nitrates are undetectable, phosphates are not lower than 0.3, even after I add GFO. Some times it reached 0.6!

KH, Ca, Mg are at NSW levels.

There’s two events that came to my attention: first, chaeto had a fast grow and suddenly start dying off. Once I started dosing triton core7, they started to grow again.

Second, while chaeto was growing nice and there’s not dead spot in the tank, there’s a strange bad smell coming from the tank which I presume is H2S.

So last Saturday I removed 80% of the chaeto. Checked inside the “ball” and it’s was all healthy.

On Sunday I tested phosphate and it was 0.09 which is at least 3 times lower and up to 6 times lower.

Smell was off after replacing GAC.

Sorry for all this writing, but it is needed to get to the question: was chaeto combined with Marine Pure balls removing too much nitrates at the point where organics were accumulating and producing H2S?

At this point I’m considering removing the refugium or marine pure balls.

But seeing the nitrates/ phosphates consuming by macro algae (I didn’t find data on chaeto specifically though) in the link above, I’m more prone to remove the refugium as the nitrate consumption is way over phosphates and the tank seems to be nitrate limited.

Thanks !

 

[Taby]

I will be following along. Experiencing similar issues running an algae reactor in my nano aquarium.

 

[Randy Holmes-Farley]

I suppose that organics in low O2 environments might result in H2S if no nitrate is around.

I’d consider dosing nitrate in this situation, even without the smell.

 

[ZaneTer]

From personal experience it is very easy to drive nitrates and/or phosphates to detrimental levels just using a refugium with chaeto and a slimmer. I dose to maintain levels.

 

[Dan Reef]

I believe there will be lots of people having the same issue as refugium is becoming more specialized now, specially with Triton Method. In the past people used cheap lights to illuminate the refugium which didn't grew algae so fast thus not removing NO3/ PO4 to detrimental levels.

After the removal of 90% of Chaeto I also noticed a ORP increase of 50 in the peak.

Instead of adding nitrates, wouldn't be better to just reduce the refugium size? Maybe 10-20%, as recommended by Triton, is too big for some tanks, specially the ones with proper lights to grow algae.

 

[tastyfish]

High phosphates and low nitrates are not good for coral and could explain some of your corals paling and poor polyp extension. You don't know what the trace elements are like, are you still performing water changes?

In my experience, low nitrates, high phosphates and the presence of unwanted trace elements (tin, copper etc) have a very detrimental effect on coral. I have been experiencing this situation for a while.

Your macro algae growth and health is influenced by four things: 1) Light, 2) Flow, 3) Nutrient availability (NO3 & PO4) 4) Trace elements.

It's not all down to light or NO3, however low NO3 will have a limiting effect on PO4 uptake by algae.

You can try to balance NO3 uptake by reducing lighting period, however I found that algae health was affected by this, so I reverted to previous levels and learned an important lesson: Refugiums are super efficient at NO3 reduction! You need to balance your stocking against your refugium.

I stocked more fish. My nitrates are not slightly higher (0.25ppm vs 0ppm previously) and PO4 is coming down (I also learned NOT to rinse my Rowaphos).

My advice would be to try to get an ICP sent off as soon as you can. If this is not going to be possible for a while, then resume routine water changes.

Try to find a balance point between the stocking and the refugium.

Use a variety of macro algae (not just chaetomorpha).

Hope this helps

 

[Randy Holmes-Farley]

Instead of adding nitrates, wouldn't be better to just reduce the refugium size? Maybe 10-20%, as recommended by Triton, is too big for some tanks, specially the ones with proper lights to grow algae.

In this case, my recommendation of nitrate dosing vs reducing light or macroalge size was the fact that phosphate was still substantial and might rise with those methods you suggested.

 

[ZaneTer]

To be honest, for the cost of raw potassium nitrate and trisodium phosphate, I would rather keep a good sized amount of macro algae as an efficient export method and just dose to maintain a stable level. I can always give away excess chaeto. I do believe though that even if your macro was a ball 10% of total volume it would still be excessively good at removing nutrients.

 

[laverda]

You could also dose iron to remove Po4. The DSR method uses iron and algae to control Po4 and vinegar to control nitrate. My nutrients dropped too low when I was running my refugium and ATS 24/7, so I reduced the light period and the amount of iron and vinegar I was dosing. Seemed silly to have to add nitrate & phosphate. I am still fine tuning the light period and dosing. Currently dosing 6ml iron & 10ml vinegar daily on my 350 gallon system.

 

[Saltyanimals]

I have the same problem with too clean water running fuge, pellets, skimmer, macro and marine pure. 10 fish in a 65 over feeding fish and coral and still counting have detectable nitrate. Just removed pellets and reduced skimmer run time just to get No up without dosing nitrate. If it doesn’t come up will have to put some stump remover in there.

 

[Dan Reef]

I'll dose some nitrate but I'm wondering if there's a better way out. Maybe changing to caulerpa instead of chaetomorph. This link provides a very interesting data on algae nitrate and phosphate uptake. @Randy Holmes-Farley are you aware if there's something similar related to chaetomorph?

I have the same problem with too clean water running fuge, pellets, skimmer, macro and marine pure. 10 fish in a 65 over feeding fish and coral and still counting have detectable nitrate. Just removed pellets and reduced skimmer run time just to get No up without dosing nitrate. If it doesn’t come up will have to put some stump remover in there.

I believe you're using too much filtration methods

 

[Randy Holmes-Farley]

I'll dose some nitrate but I'm wondering if there's a better way out. Maybe changing to caulerpa instead of chaetomorph. This link provides a very interesting data on algae nitrate and phosphate uptake. @Randy Holmes-Farley are you aware if there's something similar related to chaetomorph?



I believe you're using too much filtration methods

IME, caulerpa racemosa is more efficient than chaeto.

 

[Dan Reef]

What about the PO4:NO3 ratio?

Thanks !

 

[Randy Holmes-Farley]

What about the PO4:NO3 ratio?

Thanks !

Which link? I don’t see one on my phone.

 

[Dan Reef]

https://web.archive.org/web/2004072...482/Kaneohe Bay algae N-P Larned Mar Biol.pdf

At page 415, Table2 shows the ratio between N and P. For Caulerpa, for example, the for every 1P there was 148.7 N.

Codium, however, for every 1P there was 33.4.

 

[Randy Holmes-Farley]

https://web.archive.org/web/2004072...482/Kaneohe Bay algae N-P Larned Mar Biol.pdf

At page 415, Table2 shows the ratio between N and P. For Caulerpa, for example, the for every 1P there was 148.7 N.

Codium, however, for every 1P there was 33.4.

OK, I see what you are talking about. Yes, there is some variation in the N ratio between different species. That would presumably impact the total uptake in a reef, but I'm not sure how that knowledge is best used by reefers. Do you have an idea?

FWIW, combining species sometimes (often?) does not work out because the most efficient species will often win out. In my case., i started with many end ended with only Caulerpa racemosa.

 

[Dan Reef]

OK, I see what you are talking about. Yes, there is some variation in the N ratio between different species. That would presumably impact the total uptake in a reef, but I'm not sure how that knowledge is best used by reefers. Do you have an idea?

FWIW, combining species sometimes (often?) does not work out because the most efficient species will often win out. In my case., i started with many end ended with only Caulerpa racemosa.

A tank like mine that consume much more NO3 than PO4 would benefit by algae that has a lower ratio. There're several tanks with this issue, maybe their algae, which is usually chaeto, are consuming too much nitrate and much less than required phosphate.

 

[tastyfish]

A tank like mine that consume much more NO3 than PO4 would benefit by algae that has a lower ratio. There're several tanks with this issue, maybe their algae, which is usually chaeto, are consuming too much nitrate and much less than required phosphate.

I have always run a mixed algae bed. It does take some management to stop it being taken over (ok, I've been lax on this), but I believe it helps to have a mix of algaes with different growth and uptake rates and as one dies back, another takes its place.

 

[Randy Holmes-Farley]

A tank like mine that consume much more NO3 than PO4 would benefit by algae that has a lower ratio. There're several tanks with this issue, maybe their algae, which is usually chaeto, are consuming too much nitrate and much less than required phosphate.

I think that is almost always the experience due, at least in part, to denitrification which reduces nitrate and not appreciably phosphate. [emoji3]

 

[jkapit]

I run a large skimmer and Chaeto in a fuge and can get Nitrates to zero very easily. When that happens the corals are not happy, the Chaeto stops growing while phosphates level rise. To adjust I dose KN03 and maintain N03 around 5ppm.

Now phosphates stay around .03 without any GFO and corals are happy. I like the fact that I have to add nutrients instead of fighting to lower them by having more than sufficient skimming and refugium.