Green Sand

[crvz]

My tank is north of ten years old, and I’ve always had a shallow sand bed. I’ve overcome some hair algae issues over the last 18-24 months following a refugium crash, so I trust my overall system health has been trending in the right direction for a while (almost no hair algae growth in the tank at this point, whereas I was siphoning large amounts every few weeks prior to this year). In the last 3-4 weeks, I’ve seen this green coloration form on the sand.

I just tested the tank, everything seems clean. Nitrates are < 1ppm, po4 is under 0.10ppm. I’ve not made any changes to the lighting, or water change regimen. My RO/DI system is up to date, I use the BRS three stage DI and it’s output is at 0 TDS (water coming out of the membrane is usually under 10 TDS, and my tap water is under 200). I’m feeding the same, skimmer production is typical.

The only tangible change I’ve made to the system was shifting from a calcium reactor to two part dosing (back in October, but don’t tell @Reefahholic), which has allowed me to maintain a higher alkalinity level and pH. Where it used to hold around 7-7.5dkh, now I’m holding it around 9.75dkh. With that, my pH range has gone from 7.8-8.1 to now a 8.2-8.5 range. Calcium is unchanged and around 475ppm, and magnesium is around 1400ppm.

any thoughts? Part of me wants to just pull out the sand bed slowly, as I kind of prefer the maintenance aspects of a bare bottom tank, but that might simply lead to a green glass and not really solve the issue. What say you people? Any great sand cleaners I should employ, or some other change to address this issue?

 

[Spare time]

Looks kinda like green cyano. I'd raise the nitrate and then dose something like waste away and eco balance once its up. I'd also put the skimmer on a timer (maybe off during the day and on at night)

 

[Reefahholic]

My tank is north of ten years old, and I’ve always had a shallow sand bed. I’ve overcome some hair algae issues over the last 18-24 months following a refugium crash, so I trust my overall system health has been trending in the right direction for a while (almost no hair algae growth in the tank at this point, whereas I was siphoning large amounts every few weeks prior to this year). In the last 3-4 weeks, I’ve seen this green coloration form on the sand.

I just tested the tank, everything seems clean. Nitrates are < 1ppm, po4 is under 0.10ppm. I’ve not made any changes to the lighting, or water change regimen. My RO/DI system is up to date, I use the BRS three stage DI and it’s output is at 0 TDS (water coming out of the membrane is usually under 10 TDS, and my tap water is under 200). I’m feeding the same, skimmer production is typical.

The only tangible change I’ve made to the system was shifting from a calcium reactor to two part dosing (back in October, but don’t tell @Reefahholic), which has allowed me to maintain a higher alkalinity level and pH. Where it used to hold around 7-7.5dkh, now I’m holding it around 9.75dkh. With that, my pH range has gone from 7.8-8.1 to now a 8.2-8.5 range. Calcium is unchanged and around 475ppm, and magnesium is around 1400ppm.

any thoughts? Part of me wants to just pull out the sand bed slowly, as I kind of prefer the maintenance aspects of a bare bottom tank, but that might simply lead to a green glass and not really solve the issue. What say you people? Any great sand cleaners I should employ, or some other change to address this issue?

My first plan of action would be bacteria and also looking at the entire chemistry as a whole. You’d be surprised what trace elements can do for the microbial community.

Other options:

Maybe bring the PO4 down a little and the NO3 up. Like 0.03 and 3 or 0.05 and 5. WWC runs one of their show tanks with lower PO4 like this that has sugar fine sand and it seems to work for them.

The grain of that sand is quite large so that makes it easier to grow algae. You might want to reduce your photo period, turn down the red, or lower the intensity.

A gravel Vac may help by turning the sand over. Nassarius snails work well too.

Or you could try to change the sand to a smaller grain size which will be easier to vac and better for the snails to cruz through to keep it turned over. A lot of different op

 

[Shooter6]

You didn't mention what lights your using, or their age, but did say the system is north of ten years old if I read right.
Now I'm not saying this is your problem, but have you considered the age of the fixtures if led, or bulbs if mh or t5? Spectrum shift does occur with all types of lights with age, and may be a partial cause of your issue.
Again I am not stating it is the issue, just putting out a possibility to consider.

 

[Spare time]

deleted

 

[crvz]

Looks kinda like green cyano. I'd raise the nitrate and then dose something like waste away and eco balance once its up. Calcium reactors add phosphate to the tank but as long as you have that under control then phosphate shouldn't be an issue. I'd also put the skimmer on a timer (maybe off during the day and on at night)

You might have read the wrong… I removed the calcium reactor and added 2 part dosing. Based on your replies I believe you interpreted it the other way around.

 

[crvz]

You didn't mention what lights your using, or their age, but did say the system is north of ten years old if I read right.
Now I'm not saying this is your problem, but have you considered the age of the fixtures if led, or bulbs if mh or t5? Spectrum shift does occur with all types of lights with age, and may be a partial cause of your issue.
Again I am not stating it is the issue, just putting out a possibility to consider.

Metal halides, running from 1-7pm, 250w radium 20Kk. I replaced the bulbs in December. I also have 6 reefbrite XHO 50/50 LED strips. So lighting is pretty fresh, I try to swap out bulbs at least annually.

 

[crvz]

My first plan of action would be bacteria and also looking at the entire chemistry as a whole. You’d be surprised what trace elements can do for the microbial community.

Other options:

Maybe bring the PO4 down a little and the NO3 up. Like 0.03 and 3 or 0.05 and 5. WWC runs one of their show tanks with lower PO4 like this that has sugar fine sand and it seems to work for them.

The grain of that sand is quite large so that makes it easier to grow algae. You might want to reduce your photo period, turn down the red, or lower the intensity.

A gravel Vac may help by turning the sand over. Nassarius snails work well too.

Or you could try to change the sand to a smaller grain size which will be easier to vac and better for the snails to cruz through to keep it turned over. A lot of different op

First time I tested po4 with the ULR hanna it tested at 0.04, then I tested again and it said 0.10, then a third time and it said 0.08. I can throw some GFO on though, I have it plumbed but try not to run GFO all the time.

You know as I’m reading through your thoughts on sand stirring, and the reason I wanted some ideas… I removed a 6” checkerboard wrasse from the tank right about a month ago. While I did swap in two 3” yellow canary wrasses (both species being of the halichoeres genus), the smaller pair are way less aggressive at diving through the sand in the hunt for a meal. I bet that’s the big difference that has allowed the now stagnant sand bed to grow this algae. Still might throw some other chemical solutions at the issue, though. I have a few different bacterias on hand to dose.

 

[Reefahholic]

First time I tested po4 with the ULR hanna it tested at 0.04, then I tested again and it said 0.10, then a third time and it said 0.08. I can throw some GFO on though, I have it plumbed but try not to run GFO all the time.

You know as I’m reading through your thoughts on sand stirring, and the reason I wanted some ideas… I removed a 6” checkerboard wrasse from the tank right about a month ago. While I did swap in two 3” yellow canary wrasses (both species being of the halichoeres genus), the smaller pair are way less aggressive at diving through the sand in the hunt for a meal. I bet that’s the big difference that has allowed the now stagnant sand bed to grow this algae. Still might throw some other chemical solutions at the issue, though. I have a few different bacterias on hand to dose.

Sounds like a plan. I’d hold the GFO and do the bacteria first. It’s gonna drop the nutrients naturally. If not enough…then you could deploy the GFO.

 

[Spare time]

You might have read the wrong… I removed the calcium reactor and added 2 part dosing. Based on your replies I believe you interpreted it the other way around.

Ahhhh thanks! Somehow I read that backwards. Might be ready for another cup of coffee hahah. I made the edits