A Community and Forum For Aquaponic Gardeners

Heat of grow bed medium

Anyone experience plant stress from the grow bed medium getting too hot in the Texas summer sun? I'm building a small system now of 45 gallon GB and 45 FT. I am debating rainbow rock versus expanded clay. I presume the clay will be cooler. Maybe I'm worrying about something niggly. Is this something I need to be concerned about?

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Permalink Reply by Rob Nash on January 27, 2013 at 5:50am

txdurk, we studied the different media and how they handled the Texas heat.. turns out, its not an issue.

they may heat up on the top, but dont transfer the heat much... just dont let your water get any closer than one inch bellow the surface and it should be fine. ...now how much heat are you reflecting onto the plant is another story.

FYI - i use granite and river rock,,, its served me well for four seasons... oh, and i havent had to adjust the ph for 3 years.

Permalink Reply by txdurk on January 27, 2013 at 7:23am

Thank you Gentlemen.

@Randall: I was hoping to avoid shade cloth due to cost but if I must use it I will. I am using an old 10'x20' chain link dog kennel fence as an AP area. The sides are 6' tall. If I have a problem with FT temps, since I'm using black Rubbermaid tanks, I may try placing reflectix around it to deflect the sun. I can't dig it into the ground. My area has a little grade and the soil here is very sandy & shifts way too much.

@Rob: That's good news. Having the water no closer than one inch seems counter intuitive to me. I had thought that perhaps the evaporation of the water might act like a swamp cooler. I presume not getting the roots warm or hot is the primary point.

I'm already thinking ahead to a larger system where I would have to use rainbow rock due to cost. I have no granite available here and the river rock has limestone. Rainbow rock or stalite are my only options other than expanded clay. Of the two aggregates I am thinking stalite will retain less heat. I just don't like the fact it is dark colored and has sharper edges.

Regarding PH, my tap water (coming from Lake Conroe) looks like 7.6-7.8 using crappy test strips so I'll have to remediate on a regular basis as I top up the tank.

Permalink Reply by txdurk on January 27, 2013 at 9:55am

Randall: Fantastic. I can afford that and it fits. I'm thinking 30% should I order it. What do you think? I see your link was to 40%.

Permalink Reply by txdurk on January 27, 2013 at 9:57am

txdurk said:

Randall: Fantastic. I can afford that and it fits. I'm thinking 30% should I order it. What do you think? I see your link was to 40%.