Tired Of Diatoms - Need Help

[maurizio]

OK, this is going to be long...

 
Tank started Oct 2011. ~150 l, SG ~1.002 @ 25 C, pH ~8.2, NH3&4 0 mg/l, NH2 0 mg/l, NH3 50-100 mg/l (tap 40), sand bottom. Population as per below.

July 2012: added 10 Vallisneria and 6 Boesemani Rainbowfishes.

November 2012-now: bloom of diatoms. I always had them, but until then, I was keeping them at bay with 8 Nerites, who were doing a great job, but all of a sudden the snails disappeared, went totally nocturnal (after happy months wandering day & night and eating their way around the tank), and staying totally frozen for the entire day. Two of them died soon after this change of behaviour.

Present: Lost 7 Vallis. Diatoms all over the place. Sand terribly dirty. I vac at every water change (30% weekly), but now I can't cope with this: every time I stir the sand, an incredible cloud of dust fills the tank. The removed water is brownish-black.
 
The fish appear to be doing fine (didn't really ask their opinion, though...)

So far I assumed that the high level of NO3 is responsible for the behaviour of the nerites, and consequently the diatoms going out of control (it was lower before), polluting the tank. So far I have:
- reduced the photoperiod from 8 to 6 h (at least 6 months ago), not sure it helped much
- tried Tetra Minus Pearls
- changed part of the Eheim biofilter with Symbiont filter pallets
- switched to 2 x 20% water changes per week, with perhaps some improvement.

Last week I noticed a sudden bloom the day after a salt water change (I usually change with salt water every second or third WC), so I though it could also be the salt?? I use Tropic Marin sea salt, and they clearly state it's NO3-free.

My understanding is, diatoms need silicates, AND nitrates (like most other algae). Starving them by only cutting the silicates may lead to blooms of more annoying algae, so ideally you just want them under control, rather than starving. But surely reducing NO3 would help?

So, briefly:

1) What's going on in there?

2) Should I really check for and react to silicates, as a trigger of diatoms?

3) I read about Seachem Purigen and De-nitrate. But starting with tap at 40 mg/l...???

I'm soooo tired of this, it just looks awful and hopeless.
 
Pleeease advise!

 

[levahe]

What is your lighting? High?

Why are you adding salt? The rainbow fish aren't brackish are they? I wouldn't add any salt if you dont need to.

If you have plants in your tank you need to add plant food, are you adding any?

I was in the same position as you at one time with brown algae/diatoms all over the place, it turned out that my lighting was too bright and i wasnt feeding my plants properly. Once i lowered the lighting intensity and started feeding the plants getting good growth from them the diatom problem completely went away. Once it got the ball rolling I could then return the original level of brightness and lenght of photoperiod.
You could also add ottos they like to munch the brown algae!
Adding more plants helped too.

 

[levahe]

Also a photo of the problem would be helpful

 

[EthanF]

i currently have a lot of diatoms and brown algae around, my ottos are munching on the brown algae and i have found before you go to bed, place a towel over your tank and when you wake up so say around 8am take it away- you see, the tank is receiving unessescary sunlight from 4am upwards which grows the diatoms, this would probably help somewhat it is what i do

 

[maurizio]

Here you go, just 24 hours after siphoning and water changing...

 
To answer your questions: true, the rainbows do not need salt, but they do accept small amounts; the archers do benefit of some. And it's really a pinch.
 
Lights are 2 x T5 39W.
 
I have tried so far the following plants since the beginning, just for the purpose to help a bit with the nitrates: 1. ceratophyllum demersum and java moss; 2. Vallisneria americana. 3. Limnobium levigatum. None of them made it, except for two stems of Vallis still surviving in there. True, the bottom is pure sand, so with every plant I started some careful fertilization: tablets in the ground close to the roots, and Tropica Premium Growth in the water column. These for sure trigger at least partly the blooms.
 
I'm afraid ottos won't like even this low salinity. Plus, ain't I already at the stocking limit? I actually have room for 240 l, but I keep a good part of the tank empty for the archers to shoot insects.

I though a lot of a horse-face loach, to move the sand, but that's another carnivore...
 
Here in DK we surely have very early light in the morning, but as far as I know it hits the tank for really short time, way less than 1 h.

 

[levahe]

You could try just one light bulb and see how it goes? Or remove any reflectors if there is any. I think that your problems are because your lights are too bright.

Don't try to fight the nitrate, add plant ferts to make your plants healthy and growing. The plant ferts dont cause algae, a nutrient imbalance causes algae, like if you have plenty of nitrates in the water but you are not adding the other substances the plants need or not enough of them. Your plants died because they didn't get enough food for the amount of light they receive.
You could even try liquid co2 like excel. This also acts as an algecide.
If you are low tech (no co2) then you need micros, trace elements
If you have co2 (including liquid co2) then you need micros and macros

 

[maurizio]

Many thanks Levahe,
I'm pretty sure I've tried the one-bulb option, but unfortunately they're connected in series, so I can't disconnect any. No reflectors, just the white (now yellowish) covers, which I could remove anyway.
 
But I'll definitely go the way you recommend, perhaps getting some new Vallis, fertilizing and restarting from there. The mangroves are actually doing fine.
 
Cheers
 
Maurizio

 

[levahe]

It would be worth a try, I always say its better to spend money on plants and ferts than buying nitrate removal products and other stuff which I'm sure dont really work anyway!
I took a look at your blog and the mangroves look very nice, and the fish are lovely too

 

[maurizio]

I last updated the blog in november, since then I was so depressed... The mangroves are looking great now, and fortunately the fish are totally OK.
 
I hope I'll find the energy to add some new pics, I got some good shots of the archers recently.

 

[KirkyArcher]

2-3 day Blackout period would help, also a UV steriliser if you can run to the expense, and if your head is completely battered you may find the cost is worth every penny (krone)

 

[maurizio]

Good, I did that before, but it's no harm to try again. Let the Darkness be!