Lighting Intensity

[Waterloo Kid]

I've just been on the Java Plants web site. I bought all my plants through them and they have provided good service. The problem I have is that I'm in the middle of a terrible green water algae problem. I have looked on the Java website for recommended lighting levels. It says at least 20W per cubic foot of water. I have a Rio 400 tank with the two standard 4 ft 36W bulbs. Now, at 20W per cubic foot I should have about 20 x 5x2x2.5 = 500W of lighting! Why do I then have a suspended algae problem? Popular knowledge says this is due to an excess of light and nutrients. My lights are on for 10 hours a day. I know I have a problem with high phosphate levels (tap water) but my nitrates are always below 10 ppm. Can anyone suggest a reason for my problem. I have placed Rowa Phos in the filter and cut the lighting down to about 7 hours a day. I'm hoping this will work but nothing has changed in the past few days.
I'm looking at getting some low light nutrient munching plants in the short term. Any other suggestions?

WK

 

[jams.alaskan]

I've never seen the "per cubic foot" recomendations (but I am fairly new to this), just the watts per gallon. How does it break down to watts per gallon?

ALASKA

 

[Waterloo Kid]

400 litres is approx 88 UK gallons, so with 2 x 36 W bulbs = 72 watts I'm about average I suppose. Taking into account gravel and rockscape volume it's pretty spot on.
Another case of lots of contradictory information.

WK

 

[Dubby]

The accepted norm is 2W/ US gallon. This would make your lighting extremely low

 

[Waterloo Kid]

If that's the case then why am I getting an algae bloom? Direct sunlight hits the tank for about 10 minutes a day MAX.
I tried using reflectors but the algae happened almost as soon as I started using them so they were removed. Could the spectrum of the tubes be off? One of the bulbs is over a year old now.

WK

 

[tstenback]

One of the contributing causes to any algae bloom is a high phosphate level. I would recommend using a phosphate remover for your tap water, do several water changes over the next few days and perhaps leaving the lights off for a few days. This should help get rid of the current bloom and if you keep the phosphates under control it should help stop algae blooms in the future. HTH

 

[Pescado Guy]

You will get a lot of algae even with low light levels. It will be like a brown slime. The trick is to get the right amount. What you have is way to low for live plants. I would also get some Phosguard. I just put some in my aquarium yesterday and am starting to see the phosphate levels go down. Great product!

 

[Dubby]

Waterloo kid:

To add to what the others have said......

Low nitrates can also contribute to algae growth

You need to get the balance of nutrients, light and plants right and there is no easy equation for this - more of trial and error.

 

[Waterloo Kid]

The low nitrates could well be an issue. My tank is very lightly stocked and nitrate levels have never been above 10ppm. As my tank is primarily for fish this is ideal for me. I have added Rowa Phos and I'm monitoring the levels.
I'm going to be getting a few new plants to replace some that are dying and I'm bored with. I will obviously be concentrating on low light plants. With any luck I'll be able to rediscover the crystal clear water I had a couple of months back.


Would a liquid fertiliser help or just turn my tank into 400 litres of pea soup!?

WK

 

[Dubby]

I would advise NOT to use a liquid fertiliser at this stage.

I have had a lot of success using Pro-aqua from Green Line Aquatics. You could give it a try ???........

 

[EddieW]

You should also look at changing the tubes at least every year. The light output drops away over time and you won't notice it. I think the output spectrum can also be affected which might add to your aglae problems.

HTH, Eddie

 

[Waterloo Kid]

I decided to leave the water change for two weeks instead of the usual one to try to boost nitrate levels. I tested the nitrates after two weeks and the reading came back as absolutely zero. The plants seem to be using the fish waste faster than the fish are producing it. I wouldn't say my tank is densely planted although I do have a lot of vallis in the tank. Is it known as a hungry plant?
Even with these low nutrient levels and only 6 hours of direct light a day I have still got a suspended algae problem. It's now where as near as bad as it was but the tank still glows green when the lights are on and you cannot see through the tank lengthways (5 feet).
What's my next course of action?

WK

 

[Dubby]

Do you use any other filter besides the Juwel internal one? IMO this does not always do an adequate job.

So first things first give the filter a good clean up.

Replace the first layer (white sponge) with filter wool and ....

- do a 30% water change twice a week
- clean the filter wool (not the whole filter) at every water change
- remove all the dying plants
- get some healthy plants (get fast growers like hornwort, egeria densa)

this should clear up things .....

 

[Waterloo Kid]

Well, my regime of low light periods and less food is paying off. The tank is getting back to its old look. From the front the tank is perfectly clear. From the end the water is still green although it is possible to see right to the other end now. The fish are happy and the plants haven't dropped dead so I'm happy. Once things are perfectly clear I will look at increasing the light period again in small steps.

WK

 

[Lateral Line]

I would certainly wonder about your phosphates. Algae really grow well when there are excess phosphates. You are not, by any chance, using any pH altering chemicals/buffers? These are usually made from phosphates.

Fluorescent lamps do deteriorate over time. How much so depends on the build quality of the ends caps, which in turn, is reflected in the price of the lamp. Cheap lamps dim faster and further then good quality lamps. Replace your lamps with full spectrum lamps, (5500K - 6500K), don't bother with any of the special spectrum lamps. You might also want to get some reflectors over them to increase your light - they work quite well but need to be kept clean.