Can't keep any macroalgae alive, help!

staylor1490 · Nov 19, 2021

I currently have a 3 gallon tank with 3 lbs of live rock and live sand, both which have been cured for several months now. Unfortunately, I have been consistently unable to keep macroalgae alive in my tank. I have stocked the tank with Gracilaria Hayi, Gracilaria Parvispora, Caulerpa Prolifera, and Caulerpa Mexicana but all of them have withered away and died slowly after a week. My tank parameters are a temperature of 73 degrees (I plan to stock it with dwarf seahorses), salinity of 1.023, and nitrate and ammonia levels within reasonable bounds. In water changes in weeks past, sometimes I have added new water that have been off by +-0.003 salinity. The tank does not have filtration, only a small powerhead that brings flow to all parts of the tank. I have treated the live rock with panacur to kill off any hydroids. I have an incandescent light with a spectrum of 5000K. What is causing the macroalgae in my tank to die?

Mikedawg · Nov 19, 2021

Are you "feeding" it? What are nutrient levels in your tank?

reddevilant · Nov 19, 2021

Hello! So a couple things come to mind.

-What are your nutrient levels at?

-Salinity should be kept pretty stable with macros, as with any other livestock. 0.003 doesn't sound like much but it is a big difference.

-I'm unsure what panacur is, so I don't know if that would affect it at all.

-I believe your lights should be fine but I would try to get a light rated at at least 6,500 K.

Typically if they wither or go white/translucent it means you have a nutrient deficiency. Likely either nitrates, phosphates or iron.

staylor1490 · Nov 19, 2021

nutrient levels are very high I think, there's a biofilm layer at the top of the tank. I read that high ammonia/nitrates will kill macroalgae so I got a protein skimmer.

What kind of fertilizer do you suggest?

reddevilant · Nov 19, 2021

Could you give us numbers for the nutrients? Ammonia will kill macros as it does with fish and inverts. Extremely high nitrates could as well but it's hard to tell if we don't know what levels you're at. Personally I use Chaetogro, NeoNitro, and NeoPhos for my macro tank.

staylor1490 · Nov 20, 2021

I don't have a test for minerals but my parameters are pH: 8.0, Ammonia: 0.25 ppm, Nitrite 5.0 ppm.

Subsea · Nov 21, 2021

Do you have a tank thread? How long has 3G been set up? What nutrients do you put in this tank and what lives in this tank? What light source, intensity & duration?

reefcleaners · Nov 21, 2021

staylor1490 said:
I currently have a 3 gallon tank with 3 lbs of live rock and live sand, both which have been cured for several months now. Unfortunately, I have been consistently unable to keep macroalgae alive in my tank. I have stocked the tank with Gracilaria Hayi, Gracilaria Parvispora, Caulerpa Prolifera, and Caulerpa Mexicana but all of them have withered away and died slowly after a week. My tank parameters are a temperature of 73 degrees (I plan to stock it with dwarf seahorses), salinity of 1.023, and nitrate and ammonia levels within reasonable bounds. In water changes in weeks past, sometimes I have added new water that have been off by +-0.003 salinity. The tank does not have filtration, only a small powerhead that brings flow to all parts of the tank. I have treated the live rock with panacur to kill off any hydroids. I have an incandescent light with a spectrum of 5000K. What is causing the macroalgae in my tank to die?

Difficulty with growing algae is usually light intensity related or not enough air exchange. How big is the tank and light? Is adding an air bubbler an option for the short term at least, to see if that is your issue?

staylor1490 · Nov 21, 2021

Here's what the tank looks like currently

reefcleaners · Nov 21, 2021

Is the light above it currently the one you are using to grow? It seems too weak.

staylor1490 · Nov 21, 2021

Yes. What light do you recommend? Not looking to spend more than $20. Not planning on ever keeping corals in this tank, only macroalgae.

reefcleaners · Nov 23, 2021

I googled a bit and struck out in the under $20 selection.

flyingscampi · Nov 23, 2021

I used macroalgae in my 15 gallon because I didn't want a skimmer. They are competing methods of nutrient reduction so you could try turning off the skimmer.

I keep nutrients around 15-20 ppm NO3 & 0.06 - 0.1 PO4. Buy your own test kits or take a water sample to your LFS to discover your own levels.

If your nutrient levels are within range for keeping macromedia, I would save up and buy a light designed for reef aquarium use.

Subsea · Nov 28, 2021

staylor1490 said:
I currently have a 3 gallon tank with 3 lbs of live rock and live sand, both which have been cured for several months now. Unfortunately, I have been consistently unable to keep macroalgae alive in my tank. I have stocked the tank with Gracilaria Hayi, Gracilaria Parvispora, Caulerpa Prolifera, and Caulerpa Mexicana but all of them have withered away and died slowly after a week. My tank parameters are a temperature of 73 degrees (I plan to stock it with dwarf seahorses), salinity of 1.023, and nitrate and ammonia levels within reasonable bounds. In water changes in weeks past, sometimes I have added new water that have been off by +-0.003 salinity. The tank does not have filtration, only a small powerhead that brings flow to all parts of the tank. I have treated the live rock with panacur to kill off any hydroids. I have an incandescent light with a spectrum of 5000K. What is causing the macroalgae in my tank to die?

Panacur is

Fenbendazole, which is a canine dewormer and a treatment for canine cancer.

Your cure may have been worse than hydroids. I assume you treated rock outside of tank.

All three of the macros you mentioned are fast growing, which translates to more robust light. If $20 is a problem for your lighting, then move your tank to a window for sunlight or get a low light macro like Red Grapes, Bortacladia. It is collected in 40’-120’ of water.

Tamberav · Nov 28, 2021

staylor1490 said:
I currently have a 3 gallon tank with 3 lbs of live rock and live sand, both which have been cured for several months now. Unfortunately, I have been consistently unable to keep macroalgae alive in my tank. I have stocked the tank with Gracilaria Hayi, Gracilaria Parvispora, Caulerpa Prolifera, and Caulerpa Mexicana but all of them have withered away and died slowly after a week. My tank parameters are a temperature of 73 degrees (I plan to stock it with dwarf seahorses), salinity of 1.023, and nitrate and ammonia levels within reasonable bounds. In water changes in weeks past, sometimes I have added new water that have been off by +-0.003 salinity. The tank does not have filtration, only a small powerhead that brings flow to all parts of the tank. I have treated the live rock with panacur to kill off any hydroids. I have an incandescent light with a spectrum of 5000K. What is causing the macroalgae in my tank to die?

Swap the INCANDESCENT light for a fluorescent. Good place to start.

Other lights for a small tank. Just look for something capable of growing corals or freshwater plants for a tank around your size.

Nemo&Friends · Feb 24, 2022

I was having some trouble growing macro too. Part of the reason is I had a lot of bristle worms, and they were eating the algae, especially the green caulerpa. Now that I have less worms, one of my caulerpa is starting to grow.
I use a small LED light bought at Petsmart, and place it right on the glass cover. I do not remember the exact price, but is was around $30.00.