plantbrain

No,
I did not suggest nor imply that. On a 4w/gal tank, CO2 etc and you are asking for a more difficult to maintain dosing routine for non water change methods.

While you might be able to needle out a particular tank with a particular group and biomass of plants, it is very difficult to generalize at high light/CO2.

As I recall, your CO2 levels are not easily measured.
So that is somewhat unknown.

I am suggesting a much easier method of no water changes.
So what if you cannot grow a few stem plants that many have trouble with using CO2?

You certainly do NOT need 4w/gal to grow the above mentioned plants, I didn't, neither has Jeff or many folks.

Less light would allow more wiggle room in this method.

Add CO2? Yes, I would suggest it, but I've seen R. mac in non CO2 tanks doing alright, not well, but alright.

Not many grow L inciliata, I've done well with it. Never tried in in a non CO2 tank, so I could not say.

Some plants will surprise you though.........

Regards,
Tom Barr

Error

I am going to try your system, Edward. I tested the water at the end of last week and got 50+/5+ NO3/PO4. That's not really what I want.

Tank Statistics:
46 gallons
5.5 watts per gallon 6700K and 10000K power compact
Gravel substrate with soil underlayer
Pressurized CO2 system
High bioload

(Key: SS = Standard solution, PF = PO4-FREE solution, Mg = Magnesium solution, T = Trace solution)

(week.day)
1.1: 90% water change before dose
1.1: 3 mL SS, 3 mL Mg, 5 mL T
1.2: 3 mL SS, 3 mL Mg, 5 mL T
1.3: 3 mL SS, 3 mL Mg, 5 mL T
1.4: 3 mL SS, 3 mL Mg, 5 mL T
1.5: 3 mL SS, 3 mL Mg, 5 mL T
1.6: 3 mL SS, 3 mL Mg, 5 mL T
1.7: 3 mL SS, 3 mL Mg, 5 mL T
1.7 Test results ~5.5 hours after dose: NO3: ~15 ppm, PO4: 5+ ppm
2.1 Test results ~1 hour after lights came on and before dose: NO3: ~10 ppm, PO4: 5+ ppm
Switching to PO4-FREE solution
2.1: 3 mL PF, 3 mL Mg, 5 drops T
2.2: 3 mL PF, 3 mL Mg, 5 drops T
2.3: 3 mL PF, 3 mL Mg, 5 drops T
2.4: 3 mL PF, 3 mL Mg, 5 drops T
2.5: 3 mL PF, 3 mL Mg, 5 drops T
2.6: 3 mL PF, 3 mL Mg, 5 drops T
2.7: 3 mL PF, 3 mL Mg, 5 drops T
2.7 Test results ~10.5 hours after dose: NO3: ~25 ppm, PO4: 5+ ppm


Observations: (week.day)
2.4: Ludwigia glandulosa, L. inclinata exhibiting smaller and somewhat stunted growth. Older leaves of Ammannia gracilis darkening and beginning to rot. Color of Ammannia multiflora is now a medium green, as opposed to the yellow that it was. Bacopa australis doing well. Long internodes and slow growth in Myriophyllum mattogrossense.

2.5: Bacopa australis doing very well. Growing fast. Haven't seen this good of growth since I bought it.

Edward

Error,
If I understand correctly, you started with water 50+/5+ NO3/PO4? No, good. You need to flush that away and start clean. It's easier.

Ok, ... no problem, now you have NO3 ~15 ppm, PO4 5+ ppm. Clearly you done it right as you switched to PO4-FREE solution now. Keep dosing the same amount of 3ml a day until your PO4 goes down.

An excellent example of starting up PPS, Perpetual Preservation System. It will stabilize soon and turn out to be easy and predictable.

Edward

plantbrain

Isn't easier to do a water change and not test ? Test kits often are inaccurate. Standard solutions are much more accurate.

I can change the water in a tank faster than I can test these parameters.

Also, very few test kits will test for orthophosphate to 0.1ppm, at this low PO4 level, most of PO4, espeically if you don't do water changes/often, will be organioc forms(DOP) which plants do not use, algae do, so the test kits typically measure total PO4, so this gives you a false sense of PO4 dosing supply that is available to the plants.

Dosing routines etc, need to be scaled to the light intensity and biomass as well to run but it is certainly possible, I'm just saying the water change and redose method is much more effective and requires far less testing/less expense(good test kits are not cheap), less time to explain, works on any CO2 enriched tank at any light level, and require virtually no math.

One thing that you might wish to try out, measured rates and measure them for monocultures of particular plant species.

Rates(mole/24 hrs, grams/day etc) are far more useful, but simply because a plant takes up PO4 at a given rate, does not imply it requires that rate for healthy growth, the same is true for Fe and NO3 etc.

You may wish to try out two similar tanks one with low liught, the other with lots of light and determine the rates based on the PPS method.

I think this will give you more predictive power and usefulness on a broader spectrum of tanks/conditions.

I'd tried this method as have several other folks in the past.
Poor test kits will cause many assumptive errors.
It's a lot of testing day in/day out.

At least we know high PO4/traces does not cause algae and CO2 at 30ppm is fine/better also.

Regards,
Tom Barr

aviel

Tom,

50% water change doesn't reset your tank. U still need to measure in order to decide how much to add after water change and in order to know how 'good' you were at maintaining the levels that you targeted - no?

Aviel.

Jeff Kropp

Tom, he has 4 tanks with different light levels; look at his sig. In this thread he claims that for all 4 tanks a 3/1 N/P ratio solution must be used to maintain a 10/1 N/P ratio in each tank. Note Error's test results and compare to Edward's; unfortunatly Edward has not provide full data sets for all 4 tanks. I look forward to Errors next round of reportage and an update of Edward's.

What's the PPS method?
___
Jeff

Error

I am editing the post above every day. No sense in cluttering this thread.

Look at the title of the the thread

Gomer

Aveil, 50% doesn't completely reset, but it does prevent build up


Lets give 2 examples....suppose 50% water change and 10ppm NO3 dosing per week

1) if plants NEVEr uptake any NO3 and there are no additional sources, the most you can ever havein the tank is 20ppm.
2) suppose the tank NET NO3 at the end of the first week is 5ppm (meaning that the sum of nitrate from bacteria conversion of waste minus the nitrate consumed is 5pm), then the most NO3 you can ever build up is 15ppm

Error

Some thoughts:

Either 1) I have a bad PO4 kit (brand new Hagen) and there's no PO4 in the water to drive NO3 uptake, or 2) my bioload is high enough to affect the water column content of NO3 and PO4 significantly. There are about three dozen juvenile to young adult montezumae swords in the tank, along with about a dozen Barbus rhomboocellatus and the standard SAE/Otocinclus algae-eating crew.

Jeff Kropp

Perhaps the PPS method just never changes measured ppm of P regardless of one's routine or volumes. This is what Edward's and your data suggest.

What are the calculated ppm concentrations per tank volume for each day's dose? What does that add up to over one week in your schedual? Can you estimate your average N uptake for each week based on that information?

If your P test kit is worthless but your N test kit seems accurate you can guess at P availability by your N uptake rates. However this requires more frequent testing of N to monitor short term fluctuations. N uptake slows as P becomes less available and accelerates up to the rate of anouther limiting factor if enough P is available. So monitoring N uptake can give you important information about your tanks momentum. I think the N uptake rate can also be observed visually by noticing pearling or streaming rate changes when combined with visual clues of plant growth. Your recent subjective observations move you in that direction. Problem now is to correlate those observations with the data you have collected. Why is it that your bacopa has done so well while other plants have languished this last week?
___
Jeff