Algae disappeared and Phosphates through the roof

[stAlphonzo]

I have a rather confounding question. Since I got a 'reliable' phosphate tester, they have read on the high side , 0.055 - 0.3ish. Everything else has been pretty stable.

Nirate: 2.5 - 5
Alkalinity: 11.5
Calcium: 450 - 460
Magnesium: 1400 - 1450

I've been having really bad algae since going on vacation about 2 months ago and leaving the tank care with our house/dog sitter. Over the last two weeks, I've increased my water changes to 2-3 8-10% changes a week, siphoned and cleaned the sump and sandbed regularly (it's about 1/2" on average) and have increased diligence in scrubbing rocks, collecting the algae in a sponge and filter socks and removing them right away. Two days ago, the algae on the sandbed and glass pretty much vanished and the rocks are looking cleaner than I've seen in a long time. I've actually never been more happy with the way the tank is looking.

Now I'm feeling pretty darn proud of myself for getting rid of the algae and getting the phosphates under control (I assumed). I did a test last night to see where I got it and it literally read off the chart on the Hannah ULR Phosphorous checker. It was late and I had a few drinks so I figured I messed up the test and did another one this morning. It read 198 ppb or 0.607ppm. I did another test with the other cuvette and got the same reading. Does this make any sense? I am thinking something is wrong with the tester but it's been reasonably reliable.

Thoughts?

 

[Dan_P]

I have a rather confounding question. Since I got a 'reliable' phosphate tester, they have read on the high side , 0.055 - 0.3ish. Everything else has been pretty stable.

Nirate: 2.5 - 5
Alkalinity: 11.5
Calcium: 450 - 460
Magnesium: 1400 - 1450

I've been having really bad algae since going on vacation about 2 months ago and leaving the tank care with our house/dog sitter. Over the last two weeks, I've increased my water changes to 2-3 8-10% changes a week, siphoned and cleaned the sump and sandbed regularly (it's about 1/2" on average) and have increased diligence in scrubbing rocks, collecting the algae in a sponge and filter socks and removing them right away. Two days ago, the algae on the sandbed and glass pretty much vanished and the rocks are looking cleaner than I've seen in a long time. I've actually never been more happy with the way the tank is looking.

Now I'm feeling pretty darn proud of myself for getting rid of the algae and getting the phosphates under control (I assumed). I did a test last night to see where I got it and it literally read off the chart on the Hannah ULR Phosphorous checker. It was late and I had a few drinks so I figured I messed up the test and did another one this morning. It read 198 ppb or 0.607ppm. I did another test with the other cuvette and got the same reading. Does this make any sense? I am thinking something is wrong with the tester but it's been reasonably reliable.

Thoughts?

Are you thinking that with higher phosphate, you would see more, not less algae?

 

[stAlphonzo]

Yes, I would think that, since high phosphates is often given as a reason for many algae outbreaks. But, the other question that was in my mind but kinda forgot by the time I got to the end of the post is; is there a mechanism that too high phosphates would inhibit the algae growth?

 

[Dan_P]

Yes, I would think that, since high phosphates is often given as a reason for many algae outbreaks. But, the other question that was in my mind but kinda forgot by the time I got to the end of the post is; is there a mechanism that too high phosphates would inhibit the algae growth?

Once there Is enough phosphate, adding more will not make a difference. When the algae has all the phosphate it needs for a given amount of nitrate and light intensity, adding more has no effect on its growth. The maximum algae growth rate can be achieved at the 0.01-0.04 ppm PO4 level. Another thing to consider is that algae suffer when they receive more light than can be used based on the nitrate level, regardless of the phosphate level. I never came across a reference to PO4 inhibition of algae growth

 

[stAlphonzo]

Thanks Dan, I appreciate your input! Sorry about the bad quoting below, I seem to be having some trouble working the website today too

"Once there Is enough phosphate, adding more will not make a difference. When the algae has all the phosphate it needs for a given amount of nitrate and light intensity, adding more has no effect on its growth."

That certainly makes sense .... but in my case that algae is basically gone, not a plateau.

"Another thing to consider is that algae suffer when they receive more light than can be used based on the nitrate level, regardless of the phosphate level."

I think that makes sense. Are you saying that if the Nitrate had dropped while the light intensity remains constant, algae growth can suffer? I don't measure Nitrate very often because I have a really hard time reading any of the color graded tests so my measurements are really a best guess. It's entirely possible that value has gone down a lot lately. I am pretty sure today was 2.5 ppm while it was closer to 10 when the algae outbreak really took hold and more like 20-30 during the Spring.

"I never came across a reference to PO4 inhibition of algae growth.."

That's at least very encouraging. I was getting a bit afraid!

I think I am falling into the trap of equating correlation with causation .. that it's possible or even likely that the high phosphates contributed to the outbreak but not at all necessary that algae disappearing means the PO₄ level dropped.

Unless you or someone else corrects me, I think I'm still happy to see the algae disappear since it's possible for that to happen independently of phosphates ... but I do think I need to bring that down regardless. That level is way too high ( I think ).

 

[Dan_P]

Are you saying that if the Nitrate had dropped while the light intensity remains constant, algae growth can suffer?

Yes, algae can’t turn off photosynthesis and they need to be able to make proteins to deal with reactive oxygen species photosynthesis generates and to fix damage done by these reactive molecules. Terrestrial plants suffer this way too, turning yellow and taking on a sickly look.

 

[Tired]

Do you actually have no algae, or do you just not have pest algae? I assume your rocks are some color other than white.

When you have enough nutrients, non-pest algae can grow. If given time, it takes over your rockwork, and will outcompete pest algae for the most part. Pest algae does best in tanks where the nutrients are too low or out of whack, or tanks with a lot of clean materials. Like fresh rocks, or rocks that have been scrubbed recently.

The best way to get rid of pest algae is to let the tank mature, so it has a healthy population of non-pest algae. That may have contributed. For future reference, scrubbing rocks just scrapes off that non-pest algae, and spreads spores around, so it's not a good approach to take if you have algae issues again in the future.

 

[stAlphonzo]

Yes, algae can’t turn off photosynthesis and they need to be able to make proteins to deal with reactive oxygen species photosynthesis generates and to fix damage done by these reactive molecules. Terrestrial plants suffer this way too, turning yellow and taking on a sickly look.

That make perfect sense since I spend a lot of time with terrestrial plants as well. That statement actually resembles what I was thinking when I was observing the look of the algae .. fading in color, limp and listless.

I appreciate your input .. really helpful!

 

[KrisReef]

Did you happen to test your make up water, or the salt mix? You might check these out to make sure that you are not going to create a new problem going forward.

 

[stAlphonzo]

Do you actually have no algae, or do you just not have pest algae? I assume your rocks are some color other than white.

It's always hard to tell the difference to an extent. It seemed mostly to be GHA but probably many species were (over) growing. I don't have *no algae, but it's greatly decreased to where the green is gone from the sandbed and things look normal to where I would expect. There is Corraline algae spreading still and some small patches of turf algae, like 5-6 that are less than the size of a dime and shrinking. But the hair algae and anything else that was taking over are mostly white and lifeless and almost invisible for someone not over-analyzing the tank.

For future reference, scrubbing rocks just scrapes off that non-pest algae, and spreads spores around, so it's not a good approach to take if you have algae issues again in the future.

I certainly understand that, but as a counterpoint, just letting is sit there is not ideal either. The tank is 'mature' to the point where it's been mostly stable for the last year and I don't really change much, believing that, for the most part, rapid change is the enemy. Fish are generally healthy looking and all of the corals seem pretty happy too. When I said 'scrubbing', it's really toothbrushing off the rocks while having a clean sponge filter and clean filter socks inline to catch the debris in the overflow and changing them as soon as the water clears. Also, those actions actually correlated with a decrease in the algae growth. I was just really shocked that my PO₄ when up so dramatically at the same time.

The best way to get rid of pest algae is to let the tank mature, so it has a healthy population of non-pest algae. That may have contributed. For future reference, scrubbing rocks just scrapes off that non-pest algae, and spreads spores around, so it's not a good approach to take if you have algae issues again in the future.

So, what do you believe is the best way to decrease the pest algae in the tank? I think much of what I read focuses on water changes to decrease nutrients and manual removal to decrease spore population.

 

[stAlphonzo]

Did you happen to test your make up water, or the salt mix? You might check these out to make sure that you are not going to create a new problem going forward.

No, and you did remind me of one of the things on my list to do. I was concerned that the source water was contributing to the nutrient levels, particularly PO₄, but .. for more backstory, I had a Fire Fish die recently which I didn't notice for a day or two because he always hides (thanks to a bully Banggai Cardinal). His death certainly added to that spike as did a few other missteps, like several bad test kits convincing me that my PO₄ was 0 which caused me to dose a little PO₄ until the Hanna tester came and smashed that illusion. So, I am a little less confused about *why my PO₄ is high. I just figure the algae dying was a signal that I had gotten it under control.