How strong does the agar have to be?

[Tindomul]

When I made it I boiled it till it had that nice crystal clear quality and no undissolved particles. THen I dispensed it to its separate containers. Then I autoclaved. Did not work at 8 grams per liter but worked beautifully at 15 grams per liter.

[thegardener]

So maybe it's agar problem. I work with phytotechlab agar and 6-8 gr per liter is ok. Do you calibrate the ph before autoclaving?

[roby]

I use 5 g/l if ph medium is 5.8 without the addition of acids

If I add citric acid to adjust the pH, use 8g / l, in fact with 5 g / l does not solidify

[Royal]

Originally Posted by Tindomul

When I made it I boiled it till it had that nice crystal clear quality and no undissolved particles. THen I dispensed it to its separate containers.

Sounds about right. Whatever is going on is beyond me. I might look for a new lot of agar. Let us know what it takes to get it all worked out.

[Tindomul]

Thanks I will.

[cricketerry]

I use 7.3g/litre and have no problems with it solidifying.

[Ben Belton]

What is your pH? Agar won't solidify unless your pH is low enough. I flask Phals and shoot for a pH of about 5.8.

[Tindomul]

Really, I didn't know that. No, my pH which I have tested using hack kits is 6.7 or 7. Thats the tap, I always use distilled water which is even closer to 7.

[Phalguy]

hello!

He is right..

look here: The solidification of the agar within any growth media (GM) is pH-dependent, with an optimal range between 5.4-5.7. Usually, the application of KOH is needed to increase the pH to this range. A general guideline is about 600 µl 0.1M KOH per 250 ml GM. This entire mixture can be sterilized using the liquid cycle of an autoclave.

Source: http://en.wikipedia.org/wiki/Agar

[Mcfacker]

Most sites suggest 10g to the litre, I make mine at 12g - 1.5L ie. 8g/L, media is solid enough upon setting. Just keep mixing after every 3 pours for consistency.