Green Water!

[Chris Moreno]

So we just put up our first AP system in our campus garden on Sunday, April 29th.  The water was clear like the photo below on Friday (5/4).  Today I checked on it and it's all green.  I'm assuming it's the clear tank and grow bed along with all the sun we get throughout the day.  The water isn't thick, just green.  The fish seem happy.  They're swimming around and eating just fine.  I'm not sure how to fix it or how long it will take to fix it.  If we shade the tank, will that help?  Also, my bell siphon has been acting up and it might not have been cycling properly since Friday.  It was only trickling out and not sealing and siphoning.  I just fixed it earlier and now it's siphoning just fine.  Maybe that might have had something to do with it as well?  I have no idea.

Please help!

Thanks

[Chris Moreno]

Ah, okay.  I'll try to get some shade going for the tank asap.  How long do you think it will take for the algae to die off?

Thanks!  This one is at a CC as well, Ohlone College (Newark Campus).

Thanks for the reply.  It definitely helps.

Dave Weekz said:

Hey,  

I think your absolutely right. I have the same problem 
With my pond out back. If it even gets a day of good sun
Those colonies of algae will multiply. Shade will kill it, try a
Finer filter to get those algae solids out or add a media bed with worms
To help break down the organic matter. Hope it helps! Good luck and congrats
On the introduction to Aquaponics at your school. I'm at Houston community college 
And we have a raft and media system. More than happy to share information.

[TCLynx]

Wrap that tank up to block out the sun.  Make sure you have some extra aeration since dieing algae can consume lots of dissolved oxygen and you don't want to starve the fish for O2 while the algae is going away.

[Chris Moreno]

Okay, thanks TC!  Do you know how long it will take for the algae to die off?

TCLynx said:

Wrap that tank up to block out the sun.  Make sure you have some extra aeration since dieing algae can consume lots of dissolved oxygen and you don't want to starve the fish for O2 while the algae is going away.

[Carey Ma]

Hi there Chris, there are basically two schools in AP when raising vegetarian/ omnivorous fish. The most common is artificial confinement in clear water setups as with IBC totes. The other is doing a more natural greenwater operation. It is true and best to follow the above advice and cover (lightproof) your tank to avoid algae growth.

Greenwater operations are usually pond based and require only a bit of input as fish feed. Compost leachate or the like is added to the water to support the abundance of microorganisms that will soon coexist with your fish including mosquito larva phytoplankton and other microorganisms.

[David]

Check to make sure you are not over feeding the fish.  Excess nutrients can inspire a bloom almost instantly.  It's not uncommon for this to happen during a cycle.  Shading the tank for 3 days or more from direct sunlight will break the bloom process and give the goldfish a chance to eat that stuff up.  Also you will have algae growth on the sides of your grow bed as well once the sunlight hits it.  So you might want to shade that too to keep from suffocating the plants.  Once the roots get algae on them they're toast.

[TCLynx]

Blocking the light can take from three days to several weeks to take care of algae depending on many factors including hot good the cover is at blocking the light the algae needs.

Once the algae dies and is decomposing in the grow bed, it will help inhibit future algae blooms to an extent but you probably won't get to leave that clear tank fully exposed to the such all the time.  Best to design a cover that will be easy to open up to observe the fish but leave it mostly covered most of the time.  The fish only need to tell night from day, they don't want to be in full sun all the time.

And as Carey notes, green water culture isn't often appropriate to a small aquaponics system.  Now I do know of some green water culture being done in 5' diameter cylinder tanks but the way algae messes with pH, I wouldn't want to do it in conjunction with regular aquaponics since it would make growing the veggies difficult.

[Chris Moreno]

Oh, okay.  Thanks!  It's covered completely right now, but we're using a slightly dark green mesh/screen.  It seems to block out the sun.  Tomorrow I'll be able to put up a makeshift awning for shade.  What type of material would be best?  White tarp?

Also, the grow bed is clear.  Will that affect the amount of time it takes for the algae to die off?

TCLynx said:

Blocking the light can take from three days to several weeks to take care of algae depending on many factors including hot good the cover is at blocking the light the algae needs.

Once the algae dies and is decomposing in the grow bed, it will help inhibit future algae blooms to an extent but you probably won't get to leave that clear tank fully exposed to the such all the time.  Best to design a cover that will be easy to open up to observe the fish but leave it mostly covered most of the time.  The fish only need to tell night from day, they don't want to be in full sun all the time.

And as Carey notes, green water culture isn't often appropriate to a small aquaponics system.  Now I do know of some green water culture being done in 5' diameter cylinder tanks but the way algae messes with pH, I wouldn't want to do it in conjunction with regular aquaponics since it would make growing the veggies difficult.

[Carey Ma]

@ TC: In pond/ greenwater culture, the water often balances itself out once it is mature. The problem I had was having to filter/ screen out the algae before it goes to the plant side.

[Chris Moreno]

I have another question.  Our water pump is running off a battery charged by a solar panel with a charge controller.  When I checked this morning, the pump wasn't going and the battery was low.  The panel was in the shade so it might have just stopped for an hour.  I'm not sure.  It could have stopped in the middle of the night, but the battery is capable of keeping our pump going.

Question: How long can fish go without the water cycling/aerating the tank?  I know some people, as long as it's a cold night, unplug their pump.  This weeks temperature at night will range between the low-mid 50's.

[TCLynx]

How long the fish can go without pump/aeration will depend on fish load, size of tank and temperature.  (and if there is algae in the water, the algae will be using up dissolved oxygen during dark hours too so an algae bloom will increase the danger of loss of aeration overnight.)

[Jon Parr]

Might also try a wad of barley straw in an aerated part of the fish tank. Apparently rotting straw produces lignin, which produces hydrogen peroxide in sunlight. The peroxide kills the algae. It may give you clear water AND sunlit water for display. Also, brine shrimp and daphnia will eat free algae to the point of clarity. Worth a shot, maybe