Green water, blackouts & lessons learnt

[Ivan Choo]

I recently went through an episode of battling green water in my planted tank and would like to share my experience.

All was well with my 3 month old tank, minor algae issues, fishes were happy, MC carpeted fully and stem plants grew fast & furious. I did a massive trim and cleaned the filter, and suddenly water went cloudy. What seems like a bacteria bloom eventually turned to green water.

I attribute this trigger to possibly one if not all of the following:

• Massive trim = reduced nutrient intake. I didn't adjust my fert dosing, hence abundance of unused nutrients
• Cleaning the filter accidentally killed some bacteria which contributed to ammonia spike
• I suspect 1~2 pygmy corydoras died (almost impossible to do head-count since they're always hiding), which contributed to ammonia spike

After researching for remedies on the Internet, several water changes and reduced lighting, I decided to do a 4 days blackout that many online articles suggested. Mind you, this is my first time doing a blackout (I am quite new to this hobby).

After the blackout, lo and behold the water was clear, and as an added bonus the minor hair algae and BGA along the front glass on the substrate disappeared too. However, plants suffered as well, most notably the MC carpet (grew leggy, started to turn yellow) and buceps that were newly introduced (massive melting). The stem plants appeared stunt the following weeks, as the heaving trimming followed by blackout was a double whammy. Green water returned in a week's time.

Beaten and desperate, I went to buy a UV steriliser (13W), fixed it up, ran it, and water cleared in 1 day. Eager to bring the plants back to shape, I upped the CO2, resumed fert and increased lights (big mistake), green water returned again!. Fixed up UV for 2nd time and green water cleared in 1 day. Since then I've better managed my dosing/light/CO2, plants are recovering, and green water never came knocking.

So, here's my takeaway from this lesson.

About green water
I believe the main contributing factor is ammonia spike. High lights and abundant nutrients accelerates it. WC and lowering lights will help but can take awhile to rid it (maybe weeks). Blackout works but you need to tune tank balance up carefully until it is completely wiped out, failing so will trigger it again. Also, your plants will suffer from the blackout. UV is IMO the fastest and most cost effective fix. In hindsight, I should have went straight with the UV treatment and skip the blackout.

About blackouts
I consider this a brute force method. Will kill a slew of algaes but expect collateral damage. Stem plants seems to take it better, carpets and sensitive plants (or newly introduced plants) takes the most hit. In hindsight I should've removed the Buceps and Anubias petite since they are all tied to rocks and driftwoods. So, here's a tip for you, should you decide to do a blackout, for the love of the hobby remove as many unaffected plants as you can. House them elsewhere and spare them the blackout, they will thank you for it!

About UV sterilisers
I consider this a good investment, even for a planted tank. There's no guarantee in preventing ammonia spikes or imbalance, especially for a newbie like me who's still learning the ropes. Also, I've read it's good for treating water diseases, but that's another story. Try to get a higher wattage (mine is 13W UV for 60 litre tank with 950l/hr canister flow rate). Higher watt for higher flow rates, works faster and more efficient. Lower wattage works for green water (but longer treatment), and is not effective for treating water diseases. For now my UV is back in the box, but I may run it periodically as part of maintenance. Hopefully I can get my balance right and never use it for treatment again.

On a separate note, I have since added a prefilter to my canister filter. This allows me to remove mech-media and add more bio-media in the canister filter and dedicate it to 100% bio filtration. Flow rate wasn't reduced much and seems to be working well.

I'll be happy to hear your suggestions or criticism.

[Urban Aquaria]

Good write-up! Thanks for sharing your experience.

Yeah, green water is one of those algae types that can be difficult get rid off when it appears. Interestingly, it can also be a challenge to generate and sustain when you actually need it (ie. to feed fry or filter feeders).

Personally, i run a green water culture tank outdoors under direct sunlight and have to load it with crazy amounts of raw nutrients (aka aquarium waste) and fertilizers in order to keep the green water alive. If i forget to replenish the waste and ferts, or if the weather turns rainy/cloudy with less sunlight for a few days, i notice the green water will start to die off and clear up. So they do really need constant strong lights and lots of nutrients to keep alive.

Just an idea to consider, if you notice green water appearing again... perhaps you could consider adding one or two filter feeders like clams, fan shrimps or even daphnia (if you're not keeping any small fishes), they will relish the green water as a food source and you'll get to keep another interesting livestock in the tank. It could go some ways into creating a self-sustaining symbiotic system.

[Ivan Choo]

@UA thanks for the comment.
Next time when you're trying to cultivate or sustain green water culture, try ammonia. I think you may have better luck with it.
I did consider clams and daphnia and what-not, but my tank doesn't seem like a good fit (full soil substrate + carpet plant + rasboras). Besides, I'm still a beginner and not sure if I can keep such specialised system going. Don't wanna go from ridding green water to cultivating it. It's like solving a problem with another problem! Haha.

[Realcaster]

When I was keeping Japanese top view ranchu many moons ago, green water cultivation is not that difficult with lots of goldfish Poos and sunlight no other fertilizer or plants required... The system balanced by itself

[Ivan Choo]

I think green water is harmless to faunas. In fact I suspect they even love it. Severe green water may block out light from plants though. It's just such an eye sore in a planted tank.

[Urban Aquaria]

When I was keeping Japanese top view ranchu many moons ago, green water cultivation is not that difficult with lots of goldfish Poos and sunlight no other fertilizer or plants required... The system balanced by itself

Yeah, goldfish tanks and ponds grow green water very easily. I've also been thinking about keeping a larger outdoor tub with goldfish and just overfeed them to generate green water too, have to sort out the space for it.

[jackychun]

May I know what is the benefits of green water?


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[tetrakid]

When I was keeping Japanese top view ranchu many moons ago, green water cultivation is not that difficult with lots of goldfish Poos and sunlight no other fertilizer or plants required... The system balanced by itself

Yeah! One of my greatest joys is when I had a few goldfish kept in a big tank (4 ft) of green water. That was the start of my liking for green water, as I had never seen happier and healthier goldfish than those.

[Urban Aquaria]

May I know what is the benefits of green water?

Green water is a suspended form of living algae, they use nutrients and Co2 to grow, and release oxygen in the process (just like plants) so they help to remove excess nutrients and also oxygenate the water.

The suspended green water algae is also a source of food for many livestock, especially those newborn fry which are too tiny to eat normal foods, they eat green water during the initial growth period. For them its basically like swimming in food. Specialized filter feeders like clams and fan shrimps also consume green water as part of their diet.

For all its benefits, unfortunately its not a favorable effect in planted aquascaped tanks as the green algae tend to block light from plants, use up nutrients that plants need to grow... and generally make the tank look like one green container of pea soup. Aquascapers would much prefer clear pristine water, so they would usually try to eliminate such algae from their setups.

Managed to dig out a photo of one of my outdoor algae culture tanks in case anyone is curious what green water looks like...



Its just a simple plastic tank with sponge filter, containing abit of floating plants, some culled cherry shrimps and a guppy (to help eat mosquito larvae), usually can't see them though because of the thick green algae "soup".

[jackychun]

Very interesting! Thanks for your clarification. In that case, the green water is more suitable for a pond where people do not need to see crystal clear water through the glass. It reminds me to the pond in my uncle's house in the village in old days. The water was so green and he has many fishes in that pond. "Swimming in Food" should be very interesting for the fishes, I guess.


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[Ivan Choo]

Someone PM me with questions, unfortunately I can't PM back so replying here.


Regarding the UV steriliser, I didn't notice any significant impact on temperature when running it. The longest I've used it was for 3 consecutive days. As with any inline equipment, it does slow down flow rate, hence it's not a permanent fixture for me.


It is very effective against green water, and any bacteria or parasites that are water borne. However, it won't impact anything that is not in the water column, e.g. algae growing on your hardscape.


Also, low wattage UV (9W?) is good enough to treat green water. For treating diseases, you'll need higher wattage coupled with appropriate flow rate. Too high flow rate + low wattage, water will just pass through the UV before the light can kill any water borne organism. I'm using 13W with good results with green water, don't know about diseases though I haven't tried it, but I guess it should work. Price difference is not much (+$15 maybe?).

[happydanio123]

Hi there Ivan! Where did you get the UV sterilizer from? I've never experienced green water before and actually, I kind of want it so I have something to feed to my Yamato shrimp fry.

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[Ivan Choo]

I got the UV steriliser from Seaview, costs less than $50 after discount. It consider it cheap, the build quality is so-so but it works. Better brands (e.g. Eheim) can set you back by more than $200!

Also, avoid those in-tank UV sterilisers as I've read they are not as efficient. Get the inline type.

I think it can be a good permanent fixture for those keep sensitive shrimps or fishes!

[Ivan Choo]

All plant folks out there, UV will have an effect on your fertilisation. Specifically chelated Iron (I think).


Also I've read it is not necessary to run it 24/7 for the sake of preventing water borne diseases. The UV tube has a lifespan, recommended to change yearly.


Disclaimer: all these info were gathered from the Internet during my research, I'm no expert! Your Mileage May Vary!


http://www.americanaquariumproducts....ilization.html

http://www.aquaticquotient.com/forum...470#post246470

[Realcaster]

Very informative thank you. I will be looking for one soon

[BFG]

Ivan Choo, did you do a water change during the black out? It would lessen the free floating algae population if you did that. Did you cover all side of the tank too? I think 4 days is too long that your plants are struggling to survive, I would shorten it to 3 days. This method has been used in the reefing side too but we found out that a max of 3 days was the limit some of the coral species could take it without lighting. Oh, and blanketing all side of the tank was helpful as well as doing water change during the black out session.

[Ivan Choo]

Hi @BFG I did water change before and after the blackout. I wrapped and tapped all 4 sides and top cover with layers of black trash bag, it was 100% light proof. No feeding no water change no CO2 no peeking during the blackout. I added an airstone before wrapping that tank for the fishes.

3 days seems to be the standard for blackouts and some advise make it 4 days just to be sure. You may be right 4 days may be over stretching it. Blackout works but I'd think real hard before attempting it again. Nevertheless, was an interesting experience.

[mugenpower78]

http://www.youtube.com/watch?v=ilnitMs1LRk

Actually in nature the river bed water also got green water