Please clarify about PMDD (Composition) - The Planted Tank Forum
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post #1 of 25 (permalink) Old 04-21-2008, 06:36 PM Thread Starter
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Please clarify about PMDD (Composition)

I am thoroughly confused by the different PMDD mixtures available, but I am specifically speaking about Greg Watson's. Anyone who has purchased this recipe before, please help me! I have checked on the forums and related websites with no clear conclusion on my questions.

1. Where do you I buy this stuff?!
I see several links to Greg Watson's PMDD but none actually SELL any mixtures. They primarily go to his book which no doubt may be helpful, but does not provide my plants with any nutrients (perhaps some micro's ).

2. What is ACTUALLY in the mixture?
I have found a website, which it appears is selling Greg Watson's PMDD. However, the mixture is not consistent with that reported on the Barr report.

Barr report indicates:
http://www.barrreport.com/estimative...chy-folks.html
Plantex CSM+B
Potassium Nitrate KN03
Monopotassium Phosphate KH2PO4 (?)
Potassium Sulphate K2S04

Aquariumfertilizer.com indicates:
http://www.aquariumfertilizer.com/Store.html
Plantex CSM+B
Potassium Nitrate
Magnesium Sulfate (?)
Potassium Sulfate

3. From previous posts, it appears you should not store PO4 with Plantex as they will percipitate?
The combination listed on the Barr report would cause this to happen I believe? I'm not a chemist and I'm still trying to understand ferts, so please explain to me if I am incorrect.

4. Does the mixture from Aquariumfertilizer.com not miss out on one the of macros, Phosphates?
I was under the impression most PMDDs are the required macros, plus some micro (Plantex, for example). However this particular mix does not show any phosphates potentially missing one of the macros?


I'm not clear on which of these mixes is correct, and whether it will be sufficient. Just want a PMDD that has all the macros, plus a micro without any chemical side effects such as percipitates. Can someone please clarify the above?
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post #2 of 25 (permalink) Old 04-21-2008, 06:42 PM
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EI is not PMDD.

They use the same basic chemicals and are both for planted aquariums, but that's where the similarity ends. PMDD follows the incorrect notion that adding Phosphate is a bad thing to do and that by limiting nutrients you can control algae, also false.

There's no reason to use PMDD, it's old and obsolete. If you want liquid dosing there's a daily EI for that on Tom's site, there's also the PPS method on the APC forum. Either of those would be great.

Iron & Phosphorus when mixed together in solution will form Iron Phosphate, making both substances useless for your plants, this is why one doesn't mix PO4 with trace mixes as they contain Fe. In both PPS & Liquid EI the micro solutions are kept separate from the macro solutions.

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post #3 of 25 (permalink) Old 04-21-2008, 06:55 PM
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The "no control" BS is almost worse than the previous claims it replaced. It is not "false" that you can control algae by limiting nutrients, but you have to define your system. Whether it is "reasonable" or "practicable" in your particular aquarium is an entirely different question that has now been lost in the new brain washing that it can't be done.

fwiw -I have a PhD and have worked on restoring thousands of acres of SAV using nutrient control practices.

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post #4 of 25 (permalink) Old 04-21-2008, 07:09 PM
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You're free to believe that starving plants is an acceptable practice; however to deny plants one of the critical macro nutrients as suggested in PMDD is utterly foolish. The plants will starve and the algae will be in happy land, eagerly consuming the other available nutrients that the plants are unable to utilize.

This isn't brainwashing and our system seems to be perfectly defined considering we're discussing this on plantedtank.net. I don't claim that this information applies to anything but planted aquariums.

More to the point of the thread, the EI link from the OP discusses dry fertilizers that are added directly to the aquarium water, not mixed together prior to that action. This is why there is no risk of FePO4 forming, the chemicals are not being stored together in highly concentrated solutions, but instead diluted in the considerably larger volume of aquarium water.

It is possible to have an all-in-one solution, Tropica has that in their product called "Plant Nutrition Plus" by adjusting the pH and use of chelators. This can be done DIY-style by the information available here: http://www.theplantedtank.co.uk/allinone.htm . I haven't ever tried mixing it up because I'm perfectly happy with having two separate solutions.

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post #5 of 25 (permalink) Old 04-21-2008, 08:12 PM Thread Starter
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Thanks for the helpful answers. I was really looking for an all-in-one dry dosing mixture that I could simply purchase. Seems one does not exist except Tropica's which is rather pricey?

I know there is some debate about these things, but I'm still curious. From what I understand regarding the original post:

1. Still unknown.
2. Still unknown.
3. imeridian, are you indicating that the mixture on the barr report with PO4 and micro mixture is not correct? That it would percipitate?
4. The PMDD listed on aquariumfertilizer.com would work, but I need to dose Phosphates separately? Is that correct?
Many of the ferts I see intentionally don't have Phosphates to "prevent algae" but I'm guessing I need at least some since it is a macro required of all plant life.

It seems my best solution would be to go with that PMDD pre-mix and add a phosphate separately? I believe that would get me all macros and micros?
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post #6 of 25 (permalink) Old 04-21-2008, 09:07 PM
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1: You don't really find mixtures available, this is too variable and there is not really an incentive for the seller to mix something up, all that labor and all. Rex Grigg sells bulk fertilizers at http://rexgrigg.com/ and so does http://aquariumfertilizers.com/. It isn't at all complicated to mix together what you want. They (Aquarium Fertilizers, formerly Greg Watson) still sell PMDD dry mix.

2: This isn't a valid question. There is no right or wrong in that sense because you're comparing apples and oranges, two completely different systems. If you're asking which is PMDD, then it's the one labeled as such... and not the one labeled as EI (obviously). PMDD is a specific dosing system, as is EI, and PPS. PMDD isn't a generic term that applies to any use of fertilizer.

3: I think you need to read what I typed again. EI works perfectly fine, there's not a precipitate problem, you don't mix Fe & PO4 together except in the aquarium where the issue is nullified by water volume.

4: I suppose so, but I recommend against it. PMDD is obsolete, it should not be used. If you should have a problem with your dosing routine you'll find virtually zero support.

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post #7 of 25 (permalink) Old 04-21-2008, 09:20 PM Thread Starter
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Ok thanks imeridian for answering. Regarding question #3 I believe I understand. I thought that those macros were combined with the Plantex in an "all in one" mixture. I'm guessing by what you're saying they are sold in separate container/bags as a combo package.

More specifically to my situation, I have a 7 gallon heavily planted. Rex's Fert Combo pack has the macros and micros I need, but at these quantities I believe it would take almost a lifetime to use that much?

I would be dosing something like (2-3x week):
- 1/12 tsp KNO3 (for 10-20 ppm)
- 1/48 tsp KH2PO4 (for 1-2 ppm)
- 1/12 tsp K2SO4 (for 10-20 ppm)
- Unknown quantity of Plantex

Perhaps I've done my math wrong, but that seems like a lot of fert for those quantities. Hoping someone can point me into the right direction for the required quantities for my tank since I'm fairly new bulk/dry dosing. Would there be a place to buy the same ingredients in much smaller quantities?
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post #8 of 25 (permalink) Old 04-21-2008, 09:31 PM
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Quote:
Originally Posted by charpark View Post
Ok thanks imeridian for answering. Regarding question #3 I believe I understand. I thought that those macros were combined with the Plantex in an "all in one" mixture. I'm guessing by what you're saying they are sold in separate container/bags as a combo package.

More specifically to my situation, I have a 7 gallon heavily planted. Rex's Fert Combo pack has the macros and micros I need, but at these quantities I believe it would take almost a lifetime to use that much?

I would be dosing something like (2-3x week):
- 1/12 tsp KNO3 (for 10-20 ppm)
- 1/48 tsp KH2PO4 (for 1-2 ppm)
- 1/12 tsp K2SO4 (for 10-20 ppm)
- Unknown quantity of Plantex

Perhaps I've done my math wrong, but that seems like a lot of fert for those quantities. Hoping someone can point me into the right direction for the required quantities for my tank since I'm fairly new bulk/dry dosing. Would there be a place to buy the same ingredients in much smaller quantities?
Hi,

I bought mine from Rex too, and for my 50 gallon it would last for years. And for your 7 gallon, I think it should last a life time! yes, your math seems correct!

you can buy smaller quantity, but it's almost the same price after shipping

I suggest you get extra, once you got your 7 gallon established, I bet you will start a bigger tank.

Currently I have Crystal Red, Crystal Black, Golden/White Bee, Blue Bee, Fire Red, Dark Green, Babaulti Green, Snowball, Fire Red and Unidentified Shrimps for sale. PM me for details.
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post #9 of 25 (permalink) Old 04-21-2008, 09:31 PM
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Yes, it'll take a good long time to use all of those up, but it really wouldn't save you much money buying smaller quantities. I think dry dosed EI is excessively difficult with small aquariums. I really think this is what you're looking for.

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post #10 of 25 (permalink) Old 04-21-2008, 09:48 PM Thread Starter
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Thanks again for the help. I am beginning to notice that EI dosing is very hard as you've stated for small aquariums.

However, it seems buying a round of liquid mixes will cost the same amount as one round of dry ferts that will last a lifetime. Looks I'm going to have a lot of dry ferts on supply.
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post #11 of 25 (permalink) Old 04-21-2008, 09:51 PM
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Just to be clear, that most recent link I provided explains how to use inexpensive dry ferts to make an EI-based liquid that you can use conveniently on smaller tanks. If there's 5ml required of the macro solution for 20 gallons, you simply use about 2ml for your 7g tank.

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post #12 of 25 (permalink) Old 04-21-2008, 10:50 PM
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Quote:
Originally Posted by kvntran View Post
Hi,

I bought mine from Rex too, and for my 50 gallon it would last for years. And for your 7 gallon, I think it should last a life time! yes, your math seems correct!

you can buy smaller quantity, but it's almost the same price after shipping

I suggest you get extra, once you got your 7 gallon established, I bet you will start a bigger tank.

Man to have a small tank! I don't know what I was smoking to get me to create this monster I have here I'm looking to buy KN03 buy the 50lb sack!

Hey Imeridian, Would you mind taking a look at my EI dosing schedule. My situation is a little more complex since I can only do a 50 gallon water change at a time on my 300 gallon tank.

2 tsp. KN03 daily
5/8 tsp. KH2P04 daily
5/8 tsp. CSM+B daily
2 tsp. GH Booster with 50 gallon water change daily.

Thanks a bunch!!


Steve

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post #13 of 25 (permalink) Old 04-21-2008, 10:57 PM
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Hmm, I don't really feel qualified to advise dosing in that type of situation. I don't have any experience with EI & limited water changes and how you may need to adjust your dosing to avoid serious excess. In the one aquarium I keep that I don't do fullout EI with 50% water changes I use PPS instead with basically zero water changes.

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post #14 of 25 (permalink) Old 04-22-2008, 03:23 AM
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Originally Posted by KurtG View Post
The "no control" BS is almost worse than the previous claims it replaced. It is not "false" that you can control algae by limiting nutrients, but you have to define your system. Whether it is "reasonable" or "practicable" in your particular aquarium is an entirely different question that has now been lost in the new brain washing that it can't be done.

fwiw -I have a PhD and have worked on restoring thousands of acres of SAV using nutrient control practices.
Yes, you do have to define your system.
If you limit the plants, you will get algae.
Something will grow there and at very low nutrient levels, that will be algae.

Bachmann, Hoyer, and Crisman found no relationship between SAV, P, N and algae if a survey of over 300 lakes in subtropical Florida.

This would suggest that algae in the presence of SAV(generaly 30-50% or more coverage), is controlled not by nutrients, rather, that the SAV define the system.

If the SAV is limited(say below 50ppb P to 20ppb or so), then algae will dominate(down to 20ppb and below- out of range of the detection limits). SFWMD has a mandate for 10ppb for P which is rather tough to restore the Everglades.

The smaller the organism, the better it is at growing and competing at lower nutrient concetrations. This is normal marine pelagic ecology.

You can limit nutrients and limit algae I suppose using N and P in a planted tank, but your plants will suffer. Especially with N.

P, well, you can dramatic caes of increase O2 production when you add it and no net increase in algae.All you get is more aquatic weeds.

Algae need not be limited by nutrients, rather, light is perhaps the best solution as well as established healthy plants.

SFWMD for P references and algae vs SAV limitation ranges, and http://fishweb.ifas.ufl.edu/Bachmann/Bachmann.htm

Something else is controlling algae growth and it's likely the same thing we see in our aquariums, not P limitation.
Which is what Paul claimed.
But he did not bother to test it either.

You can limit algae, but it's rather though and simply put: not needed and does not focus on SAV needs. What SAV plants did you restore to their natural functional state and where?

Philips et al, 1978 was a popular P limiting paper, but they left out the fraction of P in the SAV but left in the P from the algae when they made their conclusions.

If you add the SAV P fraction back in, then there's no correlation, something the folks at IFAS and UF have long said.

I do agree limiting algae can be done, but it's not a good method for algae control.

Regards,
Tom Barr




Regards,
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post #15 of 25 (permalink) Old 04-22-2008, 01:27 PM
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fwiw-I use a light version of Tom's EI approach (I dose N, P & K in slight excess, and do water changes).

Imeridian-The only reason I posted was because of the absolutes you used. You're making lots of assumptions that don't always hold.You said you couldn't control algae by limiting nutrients, but that is not true. You can, but whether it is practicable in anyone's specific planted aquarium is another question. I don't currently limit nutrient(s) in the water column in my tank, but I used to in a low tech natural tank (I dosed a skewed NPK ratio) and I didn't starve my specific plants (another of your false assumptions). Depending upon the system and specific plant(s), water column dosing can be but one source of nutrients.

Tom- I agree with your tank approach in general. However, not sure I think that all your SAV cites are universally relevant. Again, it is the specific system that matters- and you need lots of data on each system on which to base management decisions. There are areas where SAV is light limited by algae, in certain cases, you can get there (increased light penetration) via nutrient control. Deeper, previously unvegetated areas become vegetated. You probably already know where I worked based on the results. Unfortunately, not too many areas have had success restoring SAV. Even in parts of the region where I worked, separate but similar systems behaved differently and we had mixed results. There are few absolutes.

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