[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Marl

> Apologizing in advance for a long post, but I wanted to get as much info as
> I could in it:
> In my 55 gallon planted tank, I have begun to get white, powdery-looking
> stuff on some of the plant leaves. It seems to be worse on the crystal val
> and E. tennellus, but has been showing a bit on some Java moss.

Moss cannot do this. It's sloughing off from some other plant.

>It makes the
> leaves feel rough and can be scraped off, but does not rub off easily. It
> only appears on the side of the tank opposite the CO2 bottles, if that makes
> any difference.

Sounds like marl. Your tank is CO2 limited.
> Tank stats: 55 US gallon, fairly heavily planted, Marineland Penguin 300
> filter, 2 DIY 1 liter yeast bottles (one refreshed every other week,
> alternately), black gravel substrate with laeterite.

DIY yeast CO2,you are CO2 limited.
> Fish: 3 otos, 3 SAEs, 2 tiger barbs, 1 Australian rainbow sp., 1 C. moorii
> (yes, rift lake cichlid, I know- but he was getting beaten literally to
> death in the Africans tank), 2 yo-yo loaches, 1 ancistrus sp.
> Plants: Lots of Java moss, Java fern, Hygro (both corymbosa and difformis),
> crystal val, giant val, aponogeton, A. reinicki, Bacopa, Rotala, E.
> tenellus, a couple smallish swords, various crypt species

A few of these will produce marl, the vals in particular. This can get
tossed around all over everything. Marl is carbonate deposits/encrustation.
Your plants are using the hard water(KH => HCO3--> CO2 + OH) to get at the
CO2. That leaves the OH- left which raises the pH. At the surface of the
leaf, the amount of OH's can get pretty high, enough to precipitate out
carbonates if the plant is growing fast. Chara, Potamogeton and vals tend to
particularly good at production of marl. This process can remove KH to the
point of making things unstable if you do not do many regular water changes.
> Maintenance: Bi-weekly 25% water change. I use Ferti-lome liquid for
> iron+traces, dosed at 1 ml 2x per week. For nitrate and potassium, I use
> solutions of nitrate of soda and muriate of potash, mostly because when I
> needed to get something, that was all I could find locally, and now I have
> pretty much all I will ever need! :) I mix the solutions at the PMDD rate,
> and was dosing daily at 1 ml each.
> Tests as of today (11/24): pH 7.4, Ammo trace, NO2 0, NO3 0, KH 4, Phosphate
> 0, temp 80F, CO2 5ppm using the KH/pH chart.

Like I said , CO2 limited. BTW, O.00ppm NO3 and PO4 are not good. Shoot for
5-10ppm of NO3 and .4-5.ppm of PO4 and a CO2 level of 20ppm-30ppm. Or just
adjust the pH to 6.6 with your CO2 gas(use only the gas to adjust your pH).
You are not get much, if any, of that CO2 gas into your aquaria's water.
> There's a picture at http://www.thirtytwopaws.com/fish/Planted%20June.htm
> Tho it's not very good, and some of the plants have changed. It was also
> taken before the white stuff appeared.
> My first guess is that something is precipitating out of solution? But I
> don't even pretend to be a chemist, so I could be way off base. And even if
> that guess is right, I've no idea what, so I wouldn't have a clue what to do
> about it! :) Any ideas, anyone?

See above. 
Tom Barr