Diatoms again?!!

[lhenson]

26 gal. set up since 2/14. I had the diatom experience at the end of the cycle and here it is again. Reading through another thread I see that it can also be caused due to high Nitrates or not vacuuming the gravel well enough. Will it just go away like it did the last time? I am assuming I should just continue to do weekly 45-50% water changes and vacuumings? I think I am vacuuming well enough, though I did have some high Nitrate readings a couple of weeks ago. I am not sure exactly how high since my API color card is worthless for Nitrates. My best guess was somewhere between 40-80. I am now using the API link posted in another thread for color comparison and have a Nitrate reading of 10. Is there anything else that could be the culprit? Would lighting have anything to do with it?

[Lady Hobbs]

High nitrates and high phosphates will cause the diatoms. Phosphates is in food. You should be doing regular maintence and water changes weekly so nitrates are not building up like that, keeping the gravel siphoned and the filter rinsed off.

Nitrates are supposed to be under 20.

[lhenson]

Thanks, Lady Hobbs, once again! Do you test for Phosphates and if so, what test do you use? API?

[madagascariensis]

I do not really know about the phosphate testing, but
have you added any new decorations, rocks, gravel, etc, ?
maybe it is leaching the silicates(or whatever its called) that the diatoms need. In that
case, you will just need to wait out until the supplies get depleted.

[escamosa]

The API test kit is good one to use.

Overstocking and a tank being new, isn't always the cause of diatoms. It can also be caused by silicates, phosphates, and high nitrates. Low light, or not enough light is another thing that can cause diatoms to start growing.

Phosphates can come from your tap water, fish food, and fish poo.
Your fishes waste is also where the nitrates come from.
And the silicates usually come from a few kinds of sands, that people use for substrates - sometimes it can come from glass.

So a few things to check.
1. You can check your tap water for phosphates.
2. Test your tank water for high nitrates.
3. What kind of substrate do you have? Play sand?

Things that you can do to treat the problem.
1. If you have high phosphates in your tap water, then you might have to concider using a product like PhosBan or Rowaphos.
2. If the tank water is the problem, and has high nitrates and/or phosphates, then you need to do large water changes - at least 50% - and gravel vacuums to bring those levels down. Do this each weak.
3. Look at your feeding technique. Are you feeding the fishes too much? Are you feeding them once a day, twice a day, or three times a day? If you're feeding them once a day, then there is a fair chance that you're dropping far too much food in the tank for them to eat in one go. Whatever food isn't eaten will settle in the substrate, rot, then it's producing nitrates/phosphates to build up in the water. I feed mine three times a day - three small serves. This way they all get some food, but it's all eaten.
4. If you have play sand as the substrate, get rid of it and get something else to replace it with. The silicates can leech out of that sand for ages, and continue to cause these diatom blooms.

[Lady Hobbs]

Agree with all above but if you have nitrates "somewhere between 40-80" and they have been up there for a couple weeks, as you say, then you simply are lacking in tank maintenance. Those high nitrates are dangerous to your fish, as well. You have to keep them much, much lower.

[lhenson]

Tank maintenance is not the issue. I am constantly at it. I do at least weekly 50% w/c's now...taking your advise. When there is an issue I do more than one a week. I did one Thursday, I am doing one tomorrow. I have always done at least weekly w/c, but usually 25's. I vacuum the gravel more than I should probably. Tank is well-kept that I can tell. I did pick up an API phosphate test kit today. I will test it tomorrow before I do a w/c and after. I will also ck the tap. I do not have play sand for substrate. I have not checked my nitrates today as I have been gone all day, but yesterday they were at 10.0. I have recorded higher Nitrate levels, but I am certain they are not accurate simply because my API card is not accurate. I am now using the link posted for Nitrate readings. The LFS always tested lower nitrate readings than I did...their color card is different than mine...theirs is the same as the link. So, apparently, I haven't had the high readings I thought I had...thankfully. I have no new decorations. I feed once a day. I always felt I'd overfeed if I feed several times a day.