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CDub
Do Not Touch the Trim
Registered: 06/08/09
Posts: 145
Last seen: 4 years, 10 months
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Gypsum Lowers pH in Substrate & Casing Mixes
#10718517 - 07/22/09 12:06 AM (14 years, 8 months ago) |
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Sulfur lowers pH slowly but surely. Calcium Carbonate will raise the pH of a substrate that is not already alkaline.
Gypsum is made of both Sulphate and Calcium Carbonate. When using Gypsum in a substrate that is, lets say 6.0pH, it holds that same substrate pH at 6.0 even after application. After the Sulphate and Calcium have time to break down, which takes awhile, the pH will eventually lower.
If 90% of your substrate is at 6.0 and you add 10% Gypsum, your pH stays at 6.0 throughout the substrates life in mycology.
Gypsum is most often used in gardening to slowly lower a mediums pH through the process of microbial oxidation in spring and summer.
Adding instead 5% Calcium-Carbonate to first increase the pH of the medium from 6.0 to between 7 and 7.5 plus the addition of 5% Gypsum will help maintain the alkaline pH through till the last flush of a spent substrate, which should still be around 7-7.5pH.
Calcium Carbonate and Gypsum should be used in our substrate mixes together at an equal rate of application
If both 5% applied by volume of Calcium Carbonate and 5% Gypsum to the volume of any materials in the Substrate or Casing mix below pH of 7.0 does not raise the pH of the Substrate or Casing material to the goal of 7.5, a small amount (.5 tsp/gallon) of Calcium Hydroxide should be added to the water used to bring the Substrate or Casing mix to field capacity of the dry mixing materials. If it still isn't at the goal of 7.5 after hydration, add another half a teaspoon of Calcium Hydroxide to the mix and let sit 20min before checking pH again before pasteurization, but this step should not be necessary.
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Edited by CDub (07/22/09 12:34 AM)
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RogerRabbit
Bans for Pleasure
Registered: 03/26/03
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Loc: Seattle
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Re: Gypsum Lowers pH in Substrate & Casing Mixes [Re: CDub]
#10718640 - 07/22/09 12:47 AM (14 years, 8 months ago) |
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Ideal pH of a substrate is 5.5 to 6.5, so you don't want to use lime in substrates. Use gypsum only, and it isn't for adjusting pH. Gypsum is for adding calcium and sulfur, both of which aid in fruitbody development, and both of which are usually lacking in most substrates. RR
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CDub
Do Not Touch the Trim
Registered: 06/08/09
Posts: 145
Last seen: 4 years, 10 months
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Re: Gypsum Lowers pH in Substrate & Casing Mixes [Re: RogerRabbit]
#10718691 - 07/22/09 01:03 AM (14 years, 8 months ago) |
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so substrate should have optimal 5.5-6.5 pH, which myc loves and so do contaminants BUT since the spawn ratio is so good and 1:2 or 1:4 that raising the pH of the Substrate to 7.5 isn't needed to keep contaminants at bay while the myc colonizes.
guess that's why you can scratch your butt while adding spawn to substrate that has pH 6.0 cause contaminants aren't as big a factor as before.
me learnz mo evern day, thanks RR
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Macropinna
Knowledgeable Newbie
Registered: 02/27/09
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Re: Gypsum Lowers pH in Substrate & Casing Mixes [Re: CDub]
#10719131 - 07/22/09 05:21 AM (14 years, 8 months ago) |
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I have home brewing books that state that gypsum lowers pH. That belief has been debunked on this site. Newer brewing texts say that it increases water hardness. This is true, but not particularly useful in the mashing process, so I don't think that most home brewers know why they add gypsum.
Gypsum is calcium sulfate. It does not contain calcium carbonate.
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CDub
Do Not Touch the Trim
Registered: 06/08/09
Posts: 145
Last seen: 4 years, 10 months
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Re: Gypsum Lowers pH in Substrate & Casing Mixes [Re: Macropinna]
#10719161 - 07/22/09 05:38 AM (14 years, 8 months ago) |
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Quote:
Macropinna said: I have home brewing books that state that gypsum lowers pH. That belief has been debunked on this site. Newer brewing texts say that it increases water hardness. This is true, but not particularly useful in the mashing process, so I don't think that most home brewers know why they add gypsum.
Gypsum is calcium sulfate. It does not contain calcium carbonate.
Gypsum is useful in lowering the acidy of wine
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wygram
Myconaut
Registered: 01/28/07
Posts: 573
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Re: Gypsum Lowers pH in Substrate & Casing Mixes [Re: Macropinna]
#10719167 - 07/22/09 05:41 AM (14 years, 8 months ago) |
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Quote:
Macropinna said: Gypsum is calcium sulfate. It does not contain calcium carbonate.
Chemical formula for Calcium sulfate is CaSO4ยท2H2O, it does not contain the carbon atom found in calcium carbonate, which is CaCO3. Natural gypsum, however, is frequently found in conjunction with limestone aka calcium carbonate, but this is usually less then 10%. The garden gypsum I have is labeled 92% pure, so I can imagine part of that may be limestone or clay used to palletize the gypsum.
Honestly, if you use a good spawn ratio, hydrate your substrate initially with a slightly lower than optimal water content, and use a good mix of ingredients there is no reason why you should worry about making the pH inhospitable for contams as the mycelium will colonize before those can germinate and take hold.
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Edited by wygram (07/22/09 05:56 AM)
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veda_sticks
Cultivator
Registered: 07/29/07
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Loc: UK
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Re: Gypsum Lowers pH in Substrate & Casing Mixes [Re: wygram]
#10719269 - 07/22/09 06:33 AM (14 years, 8 months ago) |
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bulk substrates rely in fast colinisation and the fact they are pasturised to keep contaminants at bay. Once they are fully colinised contams are of less worry since there is no freely availible food for them.
Casing layers on the other hand while not really nuitritios moulds can grow on them, and they dont colinise, mycelium will grow through it to a certain extent but theres still alot availible that moulds/bacteria can use. addition of lime shifts the ph to a range that moulds do no like but mushroom mycelium can tolerate.
The life of a substrate is too short for gypsum to have any effect on the ph of a substrate, the mycelium would also probably use most of it up before it had a chance also.
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CDub
Do Not Touch the Trim
Registered: 06/08/09
Posts: 145
Last seen: 4 years, 10 months
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Re: Gypsum Lowers pH in Substrate & Casing Mixes [Re: wygram]
#10719380 - 07/22/09 07:27 AM (14 years, 8 months ago) |
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Quote:
RogerRabbit said: Ideal pH of a substrate is 5.5 to 6.5, so you don't want to use lime in substrates. Use gypsum only, and it isn't for adjusting pH. Gypsum is for adding calcium and sulfur, both of which aid in fruitbody development, and both of which are usually lacking in most substrates. RR
Quote:
]Macropinna said: Honestly, if you use a good spawn ratio, hydrate your substrate initially with a slightly lower than optimal water content, and use a good mix of ingredients there is no reason why you should worry about making the pH inhospitable for contams as the mycelium will colonize before those can germinate and take hold.
both of these post were very helpful in afoaf upcoming substrate formulation, thank you
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