Re: [RML] Green Water!

Gary Lange (gwlange at
Mon, 11 Jan 1999 18:42:00 -1000

Just a quickie here :-) Daphnia are great in a tank with really small fish.
I keep them, when I can with fry as their babies make excellent first food.
I always forget to pull the adults though and then it's too late (they get
eaten) and I have to get some more from the outside pond. With 50 2 cm
boesemani though even if they can ingest them they will tear them up. I
would add some floating (phosphate absorbing) plants as Bruce suggested. It
might be wise to also invest in a phosphate test kit. I think I remember
someone (may or may not be this list) suggesting the Red Sea phosphate kit.
A fellow here in St. Louis was trying to tell people that our water supply
was loaded with phosphate and that was the cause of his algae blooms. I
challenged him on it and proved it with the test kit. It would be good to
test your tap water first and then the offending tank. Also compare it to
another non-greenwater tank for comparison. My guesses would be: 1) not
enough small water changes. Two cm is still small and they will take badly
to 50% water changes (at least small fish do with my water conditions and
dechlorinators). I might not pay as much attention to temperature changes
so that might be the problem but for the most part I avoid too large of a
water change on young fish. Ten to 15% might be a good start, do it daily,
especially if the test kit tells you the phosphate levels are higher than
tapwater level. Might be best to keep the temperature the same to avoid
shock. (You didn't say how often or %'s when you were doing those water
changes). If it's a phosphate/food waste problem when you finally have
changed enough water your phosphate levels will be down and your green water
will go away.
#2) Did you get a great deal on a very cheap charcoal that may be loaded
with phosphates? Anything else you're adding to that tank? Question - I
saw that the QANGFA was offering some sort of buffering reagent like
potassium phosphate, or something I could have sworn was a phosphate based
buffer. A lot of people have used things like the old sodium phosphates and
phosphoric acid to lower pH, all which are supposed to cause you problems
with algae blooms. If you've used an extra buffering compound in this
particular tank it could be a source of the phosphate & green water too.

Cutting the light out entirely could be a real bad situation although a 20 L
has a lot of surface area (~ 32 inches x 12). Maybe drop it to only 8 hours
for a while to "slow" not kill the algae. Don't forget to keep cleaning
those sponge filters and also that canister too.

So how are the Morehead river trifasciata doing????


gary lange

-----Original Message-----
From: Ernie Burns <theburns at>
To: rainbowfish at <rainbowfish at>
Date: Sunday, January 10, 1999 4:05 PM
Subject: [RML] Green Water!

> Help!! I have a 20 gallon long nursery tank with about 50 M.
>boesemani juveniles, each about 2 cm in length. The fish are doing
>great, but the water is green. Even though the tank doesn't receive any
>sunlight and the amount of tank light has been reduced to 12 hours per
>day, the problem persists. I do get some relief when I keep the light
>off for a few days, but that is not an ideal situation. I am keeping
>the temperature at 80 degrees and have 2 sponge filters and a canister
>filter (Aquaclear) running. Water changes don't bring much relief. Any
>suggestions other than living with it????
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