Re: NO2/PO4/Big Discus tank

[Thomas Barr <tcbiii at earthlink_net>]

> * NO2 and PO4 values never change in my tank. Can you advice on PO4 sources?
> I've been unable to find any KH2PO4 here in Sweden. I do have a bottle of
> "H3PO4 phosphoric acid (30%) ml".

That will work. You can figure out the amount you need either by testing
after adding it or doing the chemical math. 6-10 *drops* or so should give a
reading. If not after 15 minutes etc add this again until you get a reading.

Add it after a water change.
Hydroponics companies will sell the KH2PO4 also.
Fleet Enemas also have PO4.

> Can it be used? I know that 1 ml of the stuff lowers the pH level by 0,1.
> pH is controlled with a probe. The unit handles the CO2 automatically. (Dupla
> equipment) Wherefore it is stable both day and night.

Try lowering the pH down a .1 to .2 units and recalibrate the probe also to
make sure and double check it's not in need of replacement.
The small amount of H3PO4 you'll add will not effect the pH relative to your
tank's PO4 need/demand. You'd have to add a lot of PO4 to get the pH to
move.

> 
> Filter is Fluval 404 which should be sufficient for a 540 L tank (216
> gallons?).

Not even................
Maybe 3 of them............
See the NO2 levels that never go down.......
Also for folks that think plants use NO2..........you see they don't. A good
filter will take care of the NO2 along with good plant growth that will
remove any NH4 before it makes it to NO2.
Fish feedings/food=> NH4
KNO3=> your source for NO3.
If a little NH4 makes it over to NO2/NO3, no big deal, but it should not as
a rule generally. You have a Wimpy filter for that size tank. Not enough
current either especially for Discus. You want lots of filter for these
fish.

This is a bigger issue since if the plants are limited by PO4 etc for more
than a few days.........you'll have plants that cannot take up much NH4 and
the filter is weak/wimpy for this sized tank so you have no back up for that
NH4 that is produced in the tank. No filter to break it down fast nor plants
to take it in. Measurable NH4=> algae. Even if for a few hours, I'm not sure
how long but it's likely 30 hours or less to elicit a response. It's hard to
catch the reading also. By the time things are bad, the filter has finally
caught up with the NH4 left in the water column or the slower plant growth
etc has finally done it's job.

Add more filter/current etc
 
> <snip>
>> All are relatively easy to deal with and get rid off if good water
>> parameters are kept up on and you are actively removing the algae or using
>> herbivores. Green water requires other methods, blackout etc although
>> herbivores can easily wipe out GW if given some time.
> * Shall I interpret this as; Blackout is useless against these algea and is
> better suited for GW cases?

It'll hurt the Green hair some and the Oedogonium somewhat, but it's less
effective against these algae than the smaller species like BGA/GW etc.
Those are very small cells.
> 
> <Snip>
>> You are doing a lot of water changes daily. You'll need to add nutrients
>> back after each change.
> * The system is automated, doing nightly changes. Nutrients are added when I
> wake up, each morgning (yet to be automated)

Can you automated it to work 2x a week? I think it's generally best to do a
water change in the morning and add nutrients, N at night.
> 
> <Snip>
>> Daily water changes will not do much for Discus. Folks recommend it to keep
>> MH4/NO3 levels down. Plant tanks have low NO3 (absent NH4) generally
>> already. 
> * Reason was to keep NO3 in place. I feed a lot of daphniae and red mosquito
> larve. Since it's automated, it's not a chore :-)

If the PO4 is added, you will be needing to _add_ NO3 not remove it.
You'll find if you lift that PO4 limitation to the plants....NO3 uptake will
greatly increase as will overall plant health.

Think about PO4 limitation, is the algae really being limited here? Your
algae is doing quite well. Even though your test kits are reading absent
PO4. Although it could be a bad test kit etc, I think it goes to show that
you cannot limit algae via PO4 limitation, maybe slow an existing bloom
down, but it ain't no cure for algae. It also doesn't grow plants will
either.

So all that water changing is not needed. It's that "Balance" thing.
You are feeding good(live?) food though, add some good Frozen food along
with that. 
> 
> <Snip>
>> Java ferns do very well in my tanks, I keep the CO2 high(20-30ppm),
>> NO3(2-10ppm), PO4-(0.5ppm -1.0ppm), K-(20-40ppm),
> * How do you measure K ?
> Is it calculated or a test kit?

They make a couple of kits for K+. It's not something folks need to have
etc. The range is very large here, easy to hit by estimating. See Chuck
Gadd's site and look for his dosing calculator for K+ estimates.
For your tank if you did 40% 2x a week I'd add this after each water change:
1.5 teaspoons of KNO3
1/8 teaspoon of KH2PO4 or H3PO4(not quite certain on the amount but enough
to get to .4-.6ppm)
1.5 teaspoons of K2SO4
TMG/Flourish 30-50mls

You can measure your NO3 as an indicator for PO4/K/Traces plant uptake. If
it goes down, then your system is running good. If it stays 10ppm or less
during the 3-4 days between water changes, that's good.
If it rises much beyond 15ppm in less than 3-4 days, you'll need another
water change and increase frequency etc. I doubt you feed the fish this
much, there are only 8 fish in a 200+ gallon tank. That's low stocking
levels IMO. You should not have NO3 issues if you get the plant health
going.
Get another filter at least, that will help a great deal for both plant
health and less algae potential when the plant health possibly goes down
etc.
You can try adding the nutrients like the above routine for a few weeks.
Test and see what you think. Dosing 2x a week is fine and you might only
need to mess with it once a week. Then it'll be a nice garden rather than an
algae war. 

Regards, 
Tom Barr