densities of the upper limit of "exponential" phase of phyto

[beaniebeagle]

Anyone know what densities of tetraselmis and isocrysis go from being in exponential growth to the stationary phase??

 

[billsreef]

That's kind of like asking how long is a piece of string. There are a few culture variables that will effect that to a great degree. Size of the culture, size and shape of culture vessel, aeration, use of CO2 enrichment (or not), temperature, light, etc.

 

[beaniebeagle]

Just trying to get a guess when to feed the tank and my mandarin's Tisbe cultures without adding excess fertilizer/nutrients.

I followed your advice. I bought culture disks, f/2 etc. Took a bit longer for the isocrysis to get going, but it is. Definitely no ammonia smell like when I tried to use miracle grow. Working beautifully, thanks

 

[billsreef]

Glad to hear it's working well. Generally I find max density occurs around 1 to 2 weeks. Just got to do a bit of playing around to see where that happens with your set up

 

[dave willmore]

Has anyone checked the typical pH levels at max density and do you know at what pH they start to crash? I understand some variables would be involved like light intensity, culture depth and use of CO2 which lowers pH, but I am just asking for general levels. Thanks.

 

[billsreef]

IMO the after peak crash has to do with exhaustion of nutrients and loss of light penetration due to density, not pH.

 

[dave willmore]

Bill, I agree with you. Each algae species is a little different in it's nutrient consumption and once it exhausts a limiting element in the F/2 solution it will cease exponential growth, self shade, and the young lean algae cells will start to get older and accumulate more fats (like me!).

At that point it should be a densely colored culture and pH should rise, assuming the other factors were stable like ample light, temp and salinity.

I'd like to find the point of the culture just before that occurs (self shading and rising pH) and figure out some kind of 'electronic secchi disk' control new water and automate culture.

A turbidity or TDS meter could be used, a pH meter, or a photoelectric receptor that used a given light level on one side and a receptor on the other side to measure when a culture was densely colored and prevented light transmission. Kind of like the photoreceptor eye that turns our security lights on at night (and on foggy days) then turns it off in the morning.

If a clear soda bottle or clear plastic bag was used to hold the culture, the electric components wouldn't have to be immersed but may be wrapped in a ziplock bag to prevent damage from spills or spray.

So although every species is different, I think they would still tend to behave in the same way as nutrients became exhausted. They should have a rising pH and a darker color, assuming that light, temperature and salinity were held fairly constant.

Thoughts on a controller system?

 

[billsreef]

The pH is going fluctuate with photoperiod too much to be of use I expect. Some sort of reading of light transmission might work, aka your "electronic" sechi disk. Would probably need to spend time calibrating such a set up to each species of algae raised, and to each individual culturists set up.

 

[GreshamH]

taking pH readings won't help as per why, Bill explained.

 

[dave willmore]

Thanks, I've since learned that pH is best used for CO2 addition, not for measuring density.

 

[GreshamH]

And co2 addition really is not needed for hobbyist scale production. We use it, but we have over 2.5 million gallons in production in our peak production.

 

[dave willmore]

good point. That's a lot of second hand 2-liter cola bottles!

 

[GreshamH]

:lol: and a millions a miles of airline... joking of course, but my NDA excludes me from any real talk about how we do it