Ludwigia arcuata foreground, Rotala wallichii background

Steve Pituch said:

Edward,
.9 Watts/gallon? Please tell us more about the lighting and the tank. It seems to be quite an accomplishment at that light level.

Steve

Click to expand...

Hi,
this tank is more less used as a spare tank for plant storage. I am not interested in designing much because I am not good at it. This tank turned out quite nice so I took few pictures.

For lighting of this 90 gallon, 2 feet high tank, I use only 2 x 4 ft. lamps. I just checked the model number, Sylvania Warm White F34T12/WW/SS, the cheapest lamps from Home Depot. So it is actually even less light then I thought, it comes to 0.76 Wg.

I put 4 Lemon Tetras in there a year ago and now there is over 12 of them swimming around.

- no pump, no filter
- 1 air driven sponge filter 4" x 4" , never cleaned since installed 3 years ago
- pressurized CO2
- CO2 passive reactor, this one http://www.aquaticplantcentral.com/forum/viewtopic.php?t=1610
- water change after ~ months, only due to accidental over fertilizing
- RO water 100%

- 23C - 33C, 73F - 91F
- pH 4.0 - 4.4 electronically tested
- TDS 40 - 300 uS
- Ca2++ 10 - 20 ppm, test kit, CaSO4 and Ca2Cl dry dosing
- KH zero
- NO3 5 - 20 ppm
- PO4 0 - 0.5 ppm

Dosing daily:
- NO3 0.1 ppm KNO3
- PO4 0.01 ppm KH2PO4
- K 0.066 ppm KNO3 KH2PO4
- Mg 0.1 ppm MgSO4
- Fe 0.0005 ppm (Fe EDTA 5%, Fe DTPA 2%, Mn 2%, Zn 0.4%, Cu 0.1%, B 1.3%, Mo 0.06%)

My intention is to find the right nutrient ratio to dose DAILY, while keeping unchanged water values stability for as long time as possible.

Thank you,
Edward

Steve Pituch said:

Edward,

Are you guessing amounts based on the health of the plants, or do you have some really good test kits?

Regards,
Steve Pituch

Click to expand...

Thank you,

The principle here is to measure NO3 and PO4 weekly to adjust the daily dosing accordingly, not to get over fertilized.
For example, measurement reveals that NO3 is 20 ppm. That is too much and we don't want more of NO3. The following daily dosing will include PO4, K, Mg and Fe/TE as usual, but no more NO3. Keep dosing this until NO3 drops to 5 ppm or so and then start dosing less of the standard fertilizer again.

Standard dose:
bottle A, KNO3 27g, KH2PO4 2.5g, in 500ml
bottle B, MgSO4 168g, in 500ml
3ml / 100l
NO3 : PO4 : K : Mg
1 : 0.1 : 0.66 : 1 /[ppm]

NO3 limited dose:
bottle A, KH2PO4 2.5g, K2SO4 23g, in 500ml
bottle B, MgSO4 168g, in 500ml
3ml / 100l
NO3 : PO4 : K : Mg
0 : 0.1 : 0.66 : 1 /[ppm]

PO4 limited dose:
bottle A, KNO3 27g, in 500ml
bottle B, MgSO4 168g, in 500ml
3ml / 100l
NO3 : PO4 : K : Mg
1 : 0 : 0.63 : 1 /[ppm]

It may look complicated, but in reality, this is only 3 + 1 Mg bottle. The important fact is not to stop dosing all the other nutrients to repair the one in excess. I had no success with dosing less often then every day. I belief, if dosed less frequently, some nutrients may get absorbed too fast and the remaining nutrients won't be taken by plants even though the plants need it. They won't take it because one single nutrient is not present.

Feeding daily will ensure that all the nutrients are present in every active day. Looks like the plants can't store anything.

The Fe/TE is 24g in 500ml, 3ml / 100l -> 0.1 ppm. I dose 1 drop a day in a tank of any size. Daily fresh dose is more important then total concentration.

The easy part is, I don't care about KH and pH. The pH can never crash bellow 4.0 so why bother. This is the so called crash, obviously it does no harm. Tetras love it and plants too.

Recently, I have elevated the KH to 1.50 degree to check the CO2 concentration from the pH measurement. The plants don't seem to look any different, yet.

Test kits? Make your own concentration to calibrate the kits you use. I found that NO3 kits from Hagen Nutrafin and Aquarium Pharmaceutical have switched marine with fresh water scales. I have no idea why.

Edward