Phytoplankton?

[book_em_danio]

In my 25 gallon tank, which is my display tank in my living room, I have a small problem.

Looking from the top down to the gravel or approaching it, the water looks crystal clear. I do a 20% water change every 10-14 days.
The filter is a Tetra Whisper PF-30. Tetra sent me an extra tube so that it draws water from near the bottom, rather than the middle, as this 25 is much deeper than say a 20 Long, even a 20 high and a 29 aren't as deep... There are 18 Neons and 5 White Clouds in it.
The pH runs 6.8-7.0. My tap water is 7.0 and very soft, about 1 degree KH. Ammonia & Nitrite are always 0. Nitrate is always under 10, closer to 5 most of the time... I have not had a fatality in over 6 months and right now, everyone looks healthy.
From the bottom, looking up towards the light, there's a thin, light veil of very tiny, milky particulate, which I assume to be Phytoplankton.
I keep other tanks and this is not a problem. Those are my danio breeding tanks there are often much heavier stocked. They don't get as much light and I use Lee's Triple Flow Corner Filters there. Could it be the amount of light? Some people might say Tetra filters stink, and that may be true, but I have enough replacements to last me another 3 years (I change the carbon every 2 weeks and the biobag every 8 weeks). I start with the Tetra carbon and reload with API's Ammo-Carb the other 3 times.
Sometimes I have cleared this up using a small Lee's Triple Flow Packed with Ammo-Carb and as much floss as I can jam into the filter. It could be as simple as the old school filter is simply better?
Thanks.

[Puffer Pita]

Do you mean its like a thin layer on the surface of the water? If so, that's normal and usually means there's not enough surface aggitation. If you get a bubble wand or even just lower the level of the water a little so that the water spills out of the filter output a little better, it'll disappear.

Personally, I don't use carbon and never purchase filter replacements in any of my filters. I just get a giant pillow-size bag of hypoallergenic polyfill and use that, and the water in every tank is crystal clear. I also have a piece of sponge in each one that never gets replaced, which is the biofilter. The polyfill just gets rinsed each water change until its too dirty, then I just grab another bunch and stuff it in. The only time we ever use carbon is to remove any medications that might have been put into the tank. Oh, and I use Purigen in some of the tanks, but not all of them. There's just really no sense IMO of spending all that money on filter media when you can get a big bag of polyfill for about $2 and it lasts for ages.

[book_em_danio]

The people who make the polyfill pillow stuffing that they sell at Wal-Mart told me NOT to use their polyfill for fish filters. I figured they made both. They sent me to http://www.blueribbonpet.com/index.php
and http://www.petcetera.com/because their stuffing matrerial may contain soap, which we all know is a problem for fish. The probably make it for these brands too.
It's not on the surface floating, it is near the top more so than the bottom. It is very subtle. If I open the lid and look straight down, I can't see it. If I kneel down and look up, its the only way I can.

[Puffer Pita]

Not sure what it is then, I've never looked at my tanks from the bottom up.

I get my polyfill at Wal-Mart. Just make sure its hypoallergenic and it won't have any additives. Never had a problem with it and neither has anyone else I know who uses it. I've found that most clerks at Wal-Mart and places like that are almost completely clueless when it comes to fish so I put very little stock in any advice they try to give me. I talk to other actual aquarists and get their recommendations, and this is what I've been told repeatedly. And, as I said, I use it in all of my tanks and have never had a problem. Some get theirs at K-Mart, others at sewing type stores. Doesn't really matter, as long as its hypoallergenic polyfill.

[book_em_danio]

Originally Posted by Boxermom

Not sure what it is then, I've never looked at my tanks from the bottom up.

I get my polyfill at Wal-Mart. Just make sure its hypoallergenic and it won't have any additives. Never had a problem with it and neither has anyone else I know who uses it. I've found that most clerks at Wal-Mart and places like that are almost completely clueless when it comes to fish so I put very little stock in any advice they try to give me. I talk to other actual aquarists and get their recommendations, and this is what I've been told repeatedly. And, as I said, I use it in all of my tanks and have never had a problem. Some get theirs at K-Mart, others at sewing type stores. Doesn't really matter, as long as its hypoallergenic polyfill.

The advice came from the manufacturer. I rarely even see anyone at Wal-Mart. I get most of my supplies in trade from a LFS or from a grocery store called Redner's. They have 35 stores in PA and one in NY. They are the only grocery I know that has a selection of air pumps, heaters, power filters, etc. They even sell the floss, about $3.50 for the 7 oz bag, which is a good price...

[Puffer Pita]

Originally Posted by book_em_danio

They even sell the floss, about $3.50 for the 7 oz bag, which is a good price...

Hmm... $3.50 for 7 oz. or $2.00 for 20 oz. Yeah, I can see why they'd want you to buy their stuff labeled for fish.