green water

[amberfan1]

Hi
I have had my 4 ft fish tank set up for about 3 months and after settling down from amonia, nitrites and bacterial bloom, the water was crystal clear, recently the water has turned green, i have done a water change but after a few hours it turns green again.I have no real plants only plastic ones.Ihave an fluval 305 external filter and a fluval 3 internal filter,It is not near any windows and i have normal lights on about 8 hours a day,I HAVE 4 MEDIUM TO LARGE DISCUS ,4 TETRAS two congo tetras,2 small clown loaches.the discus have recently spawned so they must love the water.I am at my wits end with this problem as i have had tanks for 35 years and never had this problem at all,would a uv steralizer help.thanks kathy

 

[Anonymous]

green water + uv = clear water

 

[dw1305]

Hi all,

I have no real plants only plastic ones

the problem is that the filter is producing nitrates and you have no plants to use them. If you add a U.V. filter you will still have the nitrates that plants (including algae) need to grow. The fact that you have green water (this is caused by unicellular green algae) shows you have sufficient light energy for plant growth. A UV filter will kill the algae causing the green water but will lead to other algae growing in the tank (probably filamentous algae that are unaffected by the UV filter), if everything else remains the same.

You could turn the light off when you are not looking at the fish, if you have no plants it serves no useful purpose other than making the fish visible, they certainly won't mind if they only have ambient lighting. This will work by removing an essential for plant growth (light energy).

In terms of water quality the best option is to leave the light on, but swap your plastic plants for some real plants, these will utilise the nitrates, phosphates, potassium, magnesium etc. in your tank water and when you prune these the nutrients they have assimilated are removed. A really easy option is to use floating plants like Nile Cabbage, Water Fern, Duckweed, Amazon Frogbit etc., they will both shade the water column and are very easy to remove as they grow. You don't have to add any nutrients to the tank to grow these, all the time the essentials for plant growth are present, they will grow.

PM me and I will send you a starter pack of Amazon Frogbit and Salvinia, I compost some every week.

cheers Darrel

 

[ceg4048]

Hi Kathy,
Welcome to the forum!

I agree with clonitza that the fastest way to cure your green water is via UV.

What size is your tank? Are you a heavy feeder? How often do you do a water change (I assume LOTS if you're a discus keeper)? Exactly how much light is there (i.e what does "normal" mean)? Lights are generally brighter now than they have been even 10 years ago.

I assume you are pretty good at keeping fish if you've been doing it for 35 years, but I'll just mention that the root cause of green water is actually light + ammonia spikes, not nitrates. Nitrates just makes things worse, but the root cause is typically ammonia fluctuations. Even low ammonia levels (not enough to be toxic) can fluctuate enough to trigger blooms if there is enough light energy as mentioned above. This might indicate the immaturity of the tank. With dimmer lights we might have gotten away with it, but perhaps not these days.

I agree with Darrell that you should have real plants, not fake.

Cheers,