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Following quotes amply demonstrate why PMDD is synonymouswith âPHOSPHATE limitation strategyâ andhow it is not just related with micronutrients.
1. Quote form the original sears-conlin paper :--------(a) A slight excess of light, CO2, K, N, micronutrients, and trace elementsshould be maintained to allow the plants to utilize all of the availablephosphate. The authors recommend the following:ï 20-60 lumens/L illumination (about 2-4W fluorescent light per gallon),12h/dayï 10-15ppm CO2ï 3-5ppm NO3ï 0.1ppm Feï 6.5-7.0 pHSince inexpensive tests are not available for trace elements,micronutrients, or K, these items are dosed as some percentage of themeasurable nutrients. The authors have had considerable success withmixtures that duplicate the relative concentrations present in TropicaMaster Grow fertilizer [6]. For those readers wishing to "roll their own", abalanced fertilizer recipe is given in the Appendix. Various commercialaquatic plant fertilizers are also available, but it may be necessary topurchase several products to ensure complete nutrient and trace elementcoverage. Daily dosing is highly recommended because it may preventtemporary nutrient depletion, which could make phosphate available on anintermittent basis and prevent the algae from starving.------------Appendix A - Fertilizer Recipe (Poor Man's Dupla Drops)ï 1 Tbsp (~9g) Chelated Trace Element Mix (7% Fe, 1.3% B, 2% Mn, 0.06% Mo,0.4% Zn, 0.1% Cu, EDTA, DTPA)ï 2 Tsp (~14g) K2SO4 (potassium sulfate)ï 1 Tsp (~6g) KNO3 (potassium nitrate)ï 2.5 Tbsp (~33g) MgSO4.7H2O (fully hydrated magnesium sulfate, aka epsomsalts; omit if already present in trace element mix)ï 300mL distilled H2Oï 0.5mL 9M HCl (optional)

2. Quotes from PRACTICAL PMDD information on krib---
-The specifics on FeConsensus is to dose PMDD so that you accumulate and maintain around0.1mG/ltr (0.1 milli-grams/liter or 0.1 Parts Per Million) concentration ofFe (Iron) in the aquarium. Exceeding 0.2mG/ltr of Fe seems to becounterproductive.
-The specifics on NO3Consensus is a good target for aquarium NO3 is 3 to 5mG/ltr (3 to 5 PPM).
-PotassiumI don't know what a good target for K (potassium) is. It turns out to bereally difficult to measure anyway. Since PMDD is rich in K, and I've readyou can have a fair bit of excess K without harming aquatic life, I wouldn'tworry about it.
-PhosphatePMDD has no P (phosphate). According to work by Sears and Conlin, having theP in N-P-K as your limiting major fertilizer factor helps reduce algae. Ofcourse plants require some P (.02 mG/ltr a good target), but you'll no doubthave more than enough supplied by fish food and waste.

Message: 6> Date: Wed, 15 Mar 2006 14:00:17 -0800> From: Jerry Baker <jerry at bakerweb_biz>> Subject: Re: [APD] New to keeping plants.> To: aquatic plants digest <aquatic-plants at actwin_com>>> Yep, but I don't think phosphate and PMDD are related any more than say> potassium and PMDD. PMDD is just a reference to "do it yourself"> micronutrients (a Poor Man's Dupla Drops, which is mainly Fe, Mn, and B> as I recall).>>>> --> Jerry Baker>>

Message: 7Date: Thu, 16 Mar 2006 08:07:50 -0800From: Jerry Baker <jerry at bakerweb_biz>Subject: Re: [APD] pmdd -- Sears & Conlin Paper at the kribTo: aquatic plants digest <aquatic-plants at actwin_com>
That's what I had always taken it to mean, but I was getting theimpression that some were defining PMDD as, "the strategy of limitingphosphates to control algae." I just didn't understand why one wouldrefer to a strategy by the name of a fertilizer recipe. It is entirelypossible, and would not be without precedent, that I just misunderstood.I didn't intend to sound critical, but I sometimes choose my wordspoorly so that it comes across that way.
--Jerry Baker

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