Phosphates and Cyanobacteria

fixedpoint

fixedpoint

New member
About two weeks ago, Cyanobacteria showed up in my DT. The difference that I noticed was that my phosphates were at 0.09 ppm which is the highest that my DT has seen. I read about what I should do and made a few changes.

  • Regularly vacuumed the sand band and removed cyanobacteria
  • Increased water change frequency to twice a week ~25% each time
  • Cut back on feeding and fed pellets and flakes exclusively
  • Increased flow in the tank
  • Replaced the GFO in my reactor
  • Reduced the red light in my LEDs

This seemed to help lower the phosphates (especially the water changes). I got them down to 0.03 ppm which I know is still suspect because the cyanobacteria was growing. But now a week later, my phosphates are up to 0.14 ppm. Given that I have cut back feeding and I haven't had any deaths in the DT, I am wondering what the source of the phosphates is. I suspect that perhaps my BRS dry rock that I cured for 2 months and dosed with Seaklear is leaching phosphates again. Otherwise, I'm not sure what else it could be.

For an action plan, I'm going to continue my changes from above with three possible modifications.

  • Add chaeto to my refugium again (previously died)
  • Slightly increase the amount of GFO in my mixed carbon and GFO reactor
  • Increase feeding a bit - I can't starve them forever

I also am considering dosing with Seaklear in my filter socket, but I'm hesitant to do this.

Does this sound right? Any other ideas?

My tank parameters - nitrates 0, salinity 1.025 SG, pH 8.4, alkalinity 8.18 dKH, phosphates 0.14 ppm, calcium 375 ppm, magnesium 1280 ppm, temp 77 f
 
Are you using RODI water and have you tested that for phosphates?

What do you mix your water in.. A lot of plastic containers can leach phosphates.

What bio pellets do you use in your reactor? Some are known to leach phosphates back into your system once exhausted, and with readings like that you can be exhausting it quickly

Do you have a Refugium? They are great at lowering phosphates and nitrates

Do you have a DSB? And if you do how old is it, how old is your tank, it could be releasing gasses into the water column which would cause a cyano outbreak, cyano will feed on that more than phosphates.
 
My tank finished cycling 2 months ago. Since then I have added a small CUC, one clownfish, and one helfrichi firefish (today).

I am using RODI water. I changed the DI resin and filters after the first round of higher phosphates. I'll test the water for phosphates and report back.

I mix saltwater in a rubbermaid brute container. I hold my ATO water in an old Red Sea Coral Pro salt bucket.

I am using BRS GFO.

I do have a refugium although prior to the increased phosphates, the chaeto died off.

I have about 1-1.5 inches of sand + LR in my DT. My refugium has LR rubble, but not sand.
 
Hmmmmmmmmmm that all sounds right, and your sand bed isn't really old enough to release no2. How long did your tank cycle for, sounds like your intuition might be it, could be your live rock leaching. Don't add any chemicals, your phosphate levels aren't going to kill anything, just drive you nuts with algae. But with a tank this new it is normal to go through this... Usually you get Gha, diatom blooms, cyano, Dino's, ect. Definitely don't start adding chemicals, just increase water changes ( small amounts more frequently).
 
I just checked my water source. New water is 0 TDS and of course has 0 phosphates as result. I checked aged water in one bin and it also had 0 phosphates.

I cycled the tank for four weeks and saw all of the appropriate spikes and subsequent falls to zero. Before that I cured the LR for 8 weeks using Seaklear to help with leeching phosphates.
 
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IMO/E more time is necessary. I believe you are doing all the right things. I believe the cyano will pass in time. Also, IME the BRS GFO doesn't work as well as Rowphos or Xport PO. Just my experience though. Given time and your good husbandry practices I believe it will go. Hope this helps.
 
I think macroalgae will help a lot with the phosphates. Maybe your flow is insufficient over your LR in the refugium? Junk can pile up on there and leak nutrients back into your system. Just a thought.
 
Are you getting stuff deposited in your fuge? The stuff in my tank settles in the baffles or inside my skimmer body
 
I haven't seen a lot of stuff settle in the fuge, but it might be hard to tell with the LR rubble. I should probably move stuff around and check. I haven't cleaned the other two compartments yet. Which leads me to my follow up questions...

  1. How often do you clean your fuge? Your skimmer compartment? Your return compartment?
  2. What would produce excess phosphates but not nitrates? Note that I have 0.14 ppm phosphates, but 0 nitrates. Does algae growth consume more of one than the other? Does this seem to confirm LR leeching?
 
I didn't think that phosphate was a byproduct of nitrate but rather that many of the things that produce phosphates also produce nitrates.

I feed frozen pe mysis shrimp or cyclopeeze once a day. I also feed NLS pellets, new era pellets, or omega one marine flakes once a day. I haven't rinsed the frozen food in the past.
 
The next time you feed. Mix some frozen food with RO. Test the batch and see what you get for phosphate. You might be surprise.
 
phosphate brings hair algae; cyano is more a function of lighting and opportunity. It's 3 life requirements are carbon, water, and light. Phosphate at a measurable level means you have more than your algae is sucking up, and it can arrive pretty steadily as it soaks out of rocks, sometimes over a course of months.
 
So does carbon dust from a reactor increase cyanobacterial growth?

For example, I run a mix of GFO & carbon. I've heard that GFO is the harder substance. Therefore, if it is inadvertently allowed to tumble it should grind up some of the carbon increasing the carbon in the system. Does this fuel growth? Is there a way to reduce free carbon in a system? Or should we, as your post on cyanobacteria suggests, focus on the light requirement?
 
MinnFish said:
The next time you feed. Mix some frozen food with RO. Test the batch and see what you get for phosphate. You might be surprise.
Click to expand...

I tried it. Actually, I tried testing the phosphates on a variety of conditions to see if I could get insight into where the source of the phosphates.

For the experiment, I took 11 plastic cups. In each cup, I added 1 cup (.0625 gal) of liquid. In most of the cups, I also added 1/4 tsp of fish food. Some of the fish foods I strained. For the strained foods, I measured before straining. I strained the food by using a plastic cup with a small slit cut into the bottom. I mixed the water and the fish food and then measured the phosphates 10 minutes later using the Hanna Checker Phosphate Colorimeter. I plan on measuring them again tomorrow after 24 hours have elapsed.

Here is a detailed breakdown of the contents of each cup.

1. Tap Water (the source for my RODI water)
2. RODI Water
3. RODI Water with Red Sea Coral Pro Salt Mix to 1.025 SG
4. Frozen PE Mysis Shrimp + RODI Water
5. Frozen PE Mysis Shrimp strained + RODI Water
6. Frozen PE Cyclopeeze + RODI Water
7. Frozen Rod's Food + RODI Water
8. Frozen Rod's Food strained + RODI Water
9. New Life Spectrum Pellets + RODI Water
10. New Era Pellets + RODI Water
11. Omega One Marine Flakes + RODI Water

Here are the results for today. Note that the max result for the Hanna Checker is 2.5 ppm. Also, straining does remove some food, but it mostly removed a lot of the cloudy liquid.

<img src="https://docs.google.com/spreadsheets/d/1Ev_dNd--BXvREcdpR7IJ3cyvsLDs6bwB4l9c_ktbi_Q/pubchart?oid=1792855298&format=image">

Clearly, we don't feed the same amount of food by volume for each kind of food. I feed less dry food by volume than frozen food (perhaps half as much). Also, I don't feed 1/4 tsp of food currently. Probably around half of that amount. Finally, my tank has about 40 gallons of total water volume which is 640x the tested amount here.

I wish I would have began with more liquid in the cups. I am running out of measuring room.
 
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What you are proposing follows common practices. I am not familiar with the product you are proposing to dose.
 
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