# PMDD, does it still work?



## Raul-7 (Feb 4, 2004)

I was just wondering is this method(Conlin Sears Formula) still work, or is basically extinct?


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## JLudwig (Feb 16, 2004)

Raul-7 said:


> I was just wondering is this method(Conlin Sears Formula) still work, or is basically extinct?


Sort of.... Amano, Luis, quite a few I know in Europe and plenty of others still don't add macros. At good-high light levels with enough fish and good feeding (and with some NO3/PO4 in the tap) you can meet your macro needs quite nicely. This is why I say "sort of"... for sure plants need PO4, I think folks think they may have been limiting PO4 but in reality there was still enough around for good plant growth.

It lower light tanks and with heavier fish loads, just adding NO3 should work just fine. I think the method broke a little when people starting doing 3wpg tanks with no fish and good clean water - in this case PO4 can get you. But there is always something to learn some every method, and every technique has an area where it works fine. I'll stick my neck out a little here, but the common recommendation of 20-30ppm/2-3ppm NO3/PO4 weekly is way too high for most setups - in these cases Sears-Colins level of dosing is more than appropriate. Quite a lot of tanks don't need N or P, some don't need P. This higher light way of thinking is just as flawed if the setup isn't 30ppm CO2 stuff with stems and lean on fish... its important to understand whats going on, so any cookbook method is bound to fail.

Less is the better answer is just about every case. Try to get the quality and rate of growth you want with as little tampering as possible, and I think the Sears-Colins approach definately speaks to this... sort of like an Occam's Razor for horticulture  It also fosters understanding which is the most important weapon we have.

Jeff


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## Daemonfly (Mar 21, 2004)

I say it still works.

The whole point of PMDD is to customize the mix to whatever *your* tanks require. It's not a set "formula" like many places on the web think it is.


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## Hanzo (Mar 9, 2004)

Been running with nothing else for the past year or so, and my thanks seem to be blomming  And the big advantage with this over the commercial stuff is that you can ad macro or micro to fitt your tank. So, I don't think I'm going back to TMG anythime soon now


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## tsunami (Jan 24, 2004)

From the interview, it seems that Luis does add macros but only when he sees an obvious necessity in his plants. He also stated that he kept a high bioload and mentioned how it provided macro nutrients to his plants.

I like to add macros only when necessary... which basically keeps them at certain levels. 10 ppm NO3 and 2 ppm PO4 seems to be best for my really high light tank. Although the phosphate level may seem high, I can tell when it's fallen below 1.5 ppm by the sudden appearance of spot algae on the leaves of the Anubias within a day.

Luis has mentioned that he watches his Anubias carefully for figuring out how much to dose. Perhaps he can chime in?

Carlos


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## Raul-7 (Feb 4, 2004)

One reason I'm looking for "a one size approach" is that I don't really have time to fiddle around with test kits every 2/3 days. Dosing macros seperately, along with Fe/traces will be time consuming. I don't really have that much time to spare on weekdays, so I might just have to invest in the Liquidoser and follow either Gian's or Jay's formula. Carlos, I remember you don't really dose macros...you just heavily does Fe and traces. How does that work-out for you?


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## jerseyjay (Jan 25, 2004)

Hanzo said:


> the commercial stuff is that you can ad macro or micro to fitt your tank. So, I don't think I'm going back to TMG anythime soon now


Hanzo,

I have been in this hobby for a long time and I still dose TMG. 5 liters for $49 is the best price you will every get on large volume Trace Mix. Of course TMG itself is not complete fertilizer but its great addition to successfull and healthy planted tank.


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## jerseyjay (Jan 25, 2004)

Raul-7 said:


> I don't really have that much time to spare on weekdays, so I might just have to invest in the Liquidoser and follow either Gian's or Jay's formula.


Raul,

Play around for few weeks with 1 set of micros/macros and if it works, use it in liquidoser.

I use TMG as Trace addition and I found that I need to use more then recommended dose. The same applies to Iron.

Keep up your NO3 (make sure you check your TAP water and fish load) around 10-15ppm.

If NO3 is creeping up on you add additional PO4 --> levels of 1-2ppm

K levels should be sufficient just by adding KNO3. If not add additional K2SO4.

Weekly water change to even things out. Keep doing the same thing every week and you will have healthy planted tank.

There is NO MAGIC in this hobby. As for as I'm concerned it's straight forward. Sometimes you have up and downs but thats any hobby. :idea:


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## cS (Jan 27, 2004)

> One reason I'm looking for "a one size approach" is that I don't really have time to fiddle around with test kits every 2/3 days.


I haven't touched a test kit (except for pH and KH) for over 2 years. If you dose a fixed amount and keep up on water changes, nutrients will NOT accumulate past the total amount you dose per week. For example, if you dose a total of 10 ppm NO3 weekly, then regardless of the amount of your water change (as long as you're consistent), over time, your tank will equilibriate at 10 ppm NO3. And that's assuming none of the NO3 is consumed by plants.



> Dosing macros seperately, along with Fe/traces will be time consuming. I don't really have that much time to spare on weekdays, so I might just have to invest in the Liquidoser and follow either Gian's or Jay's formula.


It takes me 7.5 minutes (yes, I timed myself) to _leisurely_ dose as well as feed the fish for my two tanks. I do this every other day (4x/week). Come on Raul, you have 7.5 minutes don't you? :wink: You gotta feed the fish sometime.

Armed with Chuck's Planted Aquarium Calculator and a set of measuring spoons from your local kitchen-related store in the range of tablespoon, teaspoon, dash (1/8 tsp), pinch (1/16 tsp), smidgen (1/32 tsp), you can reliably dose everything dry (except traces) down to a 10G tank. Greg Watson has it on his website also.

But if you don't have 7.5 minutes :mrgreen:, then don't mix PO4 with the trace solution in your PMDD mix. They will react to form extremely insoluble compounds of iron phosphates that will eventually precipitate, rendering both the iron and phosphorus unavailable to plants.


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## ekim (Jan 31, 2004)

cS said:


> nutrients will NOT accumulate past the total amount you dose per week. For example, if you dose a total of 10 ppm NO3 weekly, then regardless of the amount of your water change (as long as you're consistent), over time, your tank will equilibriate at 10 ppm NO3. And that's assuming none of the NO3 is consumed by plants.


I don't know if that is correct!
If you dose 10ppm and none is used that week and you change 50% of the water the next week and add another 10ppm then you tank will have 15ppm and on and on!

Or did you mean that you dose the water you are replacing/changing to 10ppm?



cS said:


> don't mix PO4 with the trace solution in your PMDD mix. They will react to form extremely insoluble compounds of iron phosphates that will eventually precipitate, rendering both the iron and phosphorus unavailable to plants.


Totally agree there, same thing will happen with K2SO4 & CaCl.


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## tsunami (Jan 24, 2004)

> Dosing macros seperately, along with Fe/traces will be time consuming. I don't really have that much time to spare on weekdays, so I might just have to invest in the Liquidoser and follow either Gian's or Jay's formula.


And you're just in high school? Wait until you get into college and have twice as many things to do. Weekends become kind of an extension to the weekday, except you just don't have classes. 

When I was not dosing macros, my plants did fine but they did seem like they could use a little boost. I am dosing macros again and keeping my nutrients at 2 ppm PO4 and 10 ppm NO3 (more or less). The speed of plant growth and plant coloration has improved immensely, especially with the high PO4. I've also had less of an issue with spot algae, despite the fact that my Anubias nana are inches away from 4 wpg of lighting.

I find myself testing a tank less and less as it ages. I start to "know" how the tank works, what it absorbs, what happens when there's 1 ppm PO4 or 2 ppm PO4... etc.

Carlos


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## plantbrain (Jan 23, 2004)

I think the PMDD is fine, perhaps needs a little tweaking with respect to the low CO2/PO4 thing.

CO2 is one nutrient that should not be ran low if you add enrichment. The variations will help and select for algae and not plants.
Their conclusion about PO4 limiting algae is off (0.2ppm) by at least a factor close to 100 fold.

Plants will be far more limited in that case. 
You cannot kill your patient to cure a disease. 

Besides that, based on the case study, they concluded correctly.
It got many people think about macro's, that was the biggest thing.

But folks need to remember, 1.7 watt/gal on light, NO FL's etc!!!!!!!

Good fish loads etc !!!!!!!

When you scale that up, the needs for the plants can change dramatically. Tap water sources also play a large role, loike they did in my case with Marin's magic water that was loaded with PO4.
Other places have high NO3 etc. 

The rate at which you load the tank and drive it with the light energy input is going to determine the dominace.

If you are smart, you would limit the light, that would allow you the best robust variations in CO2 and nutrients making them not as critical as they are with high light.

Light is easier to control than the others also and is the main energy driver.

With 1.7 w/gal, PMDD and a fish load works fine. 
But the same could be said for a non CO2 and a fish load alone and I would bet even better long term growth and tank looks over time with the non CO2 tank.

Regards, 
Tom Barr


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## Raul-7 (Feb 4, 2004)

I know it was a great method back in those days of NO flourscent, and DIY C02...but your saying with the addition of adding PO4 seperately and tweaking in the dosage of PMDD, you can still get good results with this method even with high light and pressurized C02?


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## cS (Jan 27, 2004)

Raul,

As far as I am concerned, everyone nowadays is more or less using PMDD in that PMDD is Poor Man's Dosing Drops. That's exactly what we are all doing: we make our own fertilizers and we cater it to our specific needs. Most of us don't use commercially available all-in-one fertilizers. There's nothing in the original PMDD recipe that we don't use today. We simply tweak the numbers a bit. Heck, some of us even put them all in a single bottle like Jay Luto for example, but he's doing it mostly out of convenience. The importance is that we provide the basics (NPK+Ca/Mg+micros) in adequate concentrations. How that is attained is up to the individual aquarist.

---



> did you mean that you dose the water you are replacing/changing to 10ppm?


There's no way I would know exactly how much is required w/o the use of a good testkit...and I don't use any NO3 test kit. 

What I meant is this:

WEEK 1
Add 10 ppm => 10 ppm NO3
After 50% WC => 5 ppm

WEEK 2
Add 10 ppm => 15 ppm
After 50% WC => 7.5 ppm

WEEK 3
Add 10 ppm => 17.5 ppm
After 50% WC => 8.75 ppm

WEEK 4
Add 10 ppm => 18.75 ppm
After 50% WC => 9.375 ppm

Etc.

We see that after each successive week of water changes, the value approaches the total amount of NO3 added, never more, assuming no NO3 is being used by plants. I should have made this clearer Ekim. My apologies.


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## plantbrain (Jan 23, 2004)

Yes Raul, 

Adding PO4, more NO3, K, traces, CO2 are needed when you add more light.

The __loading rate__ is what is important.

How fast are these being used up. When the plant needs are low, there's going to be a lot more play.

This was one reason I played around with high light tanks long before many did. With faster growing, high light systems, you are forced to be more critical about CO2, NO3 etc.

But you also discover the rates of uptake of PO4, NO3, and what are the optimal CO2 saturation points(30ppm is what has been found in the research FYI).

Now if take these same parameters and apply them to low light CO2 tank, the results are nothing less than stunning and easy to control.

By driving the light higher, we have be able to go back and fully optimize the lower light tanks also.

Without high light, we would have never found out these more optimal ranges.

With water changes, 50% water changes will level off any over dosing provided the levels in the tap are constant/low etc.

The levels start approaching asymtotically to a maximum level but it is a log curve, not linear, eg the levels don't continue to increase.

Anyway, do a large water change if you are worried.

Most folks that problems with plants generally have something limiting growth, not an excess.

The other good thing about large water changes, removes the Dissolved organic PO4 and NO3/NH4 forms which select for various algae and that plants will not be able to use.

Plants prefer the inorganic labile forms, so doing large frequent water changes and dosing afterwards will provide the lower algae growth with excellent plant growth.
It also makes testing for NO3/PO4 etc easier(all inorganic forms) and many don't test at all since they can eastimate their NO3/PO4 etc just fine using that method. 


Regards, 
Tom Barr


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## Raul-7 (Feb 4, 2004)

Isn't it better to dose a little of everything daily, then to have highs-lows throughout the week?


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## JLudwig (Feb 16, 2004)

Raul-7 said:


> Isn't it better to dose a little of everything daily, then to have highs-lows throughout the week?


This is more of a religious issue methinks...  I really do think I get higher quality growth dosing daily and maintaining constant levels on my very high light tank (2x36W PCF on 15 gallons). 1x-2x weekly I think is okay at low to mid lighting levels but for some reason iron doesn't stay in the water column anywhere near as long at high light levels levels. I don't know whether this is photo-oxidation or something else (I don't think its all uptake since it doesn't scale linear with growth), something funny is going on and it happens faster at higher light levels.

Also on the APD maybe a year ago, Detlef (sp?) had posted something about stellata not stunting with daily additions of macros but it did when given a burst. I have had the same experience and also have found Rotala sp. stuntiing to also stop with daily additions...

Jeff


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