Backyard Aquaponics
A place to discuss aquaponics

7.6 it is then

don't forget that CO2 levels play a part. you think this is hard try and get your brian around the relationship / equlibrium between alkalinity (KH) and PH and calcium content of marine water!

Yes, media will dissolve but the same amount that would have had you added it seperatly.

I'd probably put a % shells in one section of your bed.

it gives you yet another micro environment which may host diverse orgs.

my work here is done!

I think 7.6 is where the shells will try and keep things.

Today I tested again and the two different tests with shells are both at 7.6 still while the sample of system water with an aerator and river rock is still falling down to 6.6 now.

The Pee Ponics system, as of about noon yesterday has it's top grow bed over the flush tank as a shell bed. The pH spiked up and was about 7.9 a few hours after the change out. This morning the pH is back around 7.5.

Steve,
I was looking at using straight shells as grow bed media. I don't know if I can get a load of two different things from pebble junction so was planning to get a load of either 6 ton river rock or 6 ton washed shells. As the bag of shells in the flush tank wasn't really keeping the pH very high, I went ahead and filled a small grow bed with it. Do you think it would be a mistake to use shell as the grow bed media? Would 7.6 be too high a pH to maintain for AP? Though the washed shell is a little more $ per ton, it is lighter so 6 ton will go further.

are they crushed shells or whole?

what is their average size

i can give you a definative answer, sorry.

i'd like to say take one for the team, but 6 ton is alot!

i recon 7.6 would be fine for AP veggies.

was maybe concerned about localised root zones being higher ph.

would LOVE for you to do a 3T shell 3T river divided bed setup then plant all the same things.

if you cant get 3T / 3T is there any AP'er close by that can go you halves?

there is always Ebay. imagine how much you could make by selling 3000 1kg lots of bagged shells

TCL, Isn't Pebble Junction great! The first time I went there I spent hours looking at all the bins. (Maybe I should get out more often). What type of fish are you going to raise? This will help determine what PH level you need and the mixture that makes up the PH level required.

Hi Joyce,
Good to see you posting again, seems you've been away a while. Yes Pebble Junction is great!
I was thinking of going with the blue tilapia though I wouldn't be opposed to attempting something more native if it were reasonable.

Steve,
I'll upload a couple pictures here of the shell. It is mixed variety and busted up though not crushed or pulverized. The price list gives it a size of 1/2" though that is a very rough estimation.

I might try and see if they would do a mixed load for me but they might be resistant to that the way the fill and weigh the trucks.

I am becoming more tempted to go for it with the shell since it is lighter and there is a strong likely hood that I will be moving within 5-6 years (not moving far though.) So long as the bacteria can colonize the shell and do their job.

Well, if the shell wants to be 7.6, that's not bad. As your organics build up, that will try to drop a little, but still a nice range. The only concern remaining that I would have is that fact that over time, each piece of shell will slowly shrink towards sand-sized. That would mean that over the (very?) long run, your bed will compact and space between pieces will reduce. Water flow dynamics will change over time. As long as you're prepared for that, I'd say go for it.

I expect that the dynamics of any grow bed and media change some over time, it is probably more a matter of degree. Since I am probably going to be moving this stuff after several years, it probably isn't such a big deal if I am going to need to refresh the media in this case.

Hum, looks like I'm leaning more and more to the shell.

you plants wont be lacking calcium. water will be hard, but i haven't had any problems.

initial spike to 8 may be due to a small percentage of the shell dust being aragonite? who knows.

go for it, girl.

Well, I called Pebble Junction today and they were willing to send a mixed load so that is what I ordered. Tomorrow should see a delivery of 3 ton 1/2 inch brown river rock along with 3 ton washed shell. There is no divider in the truck or anything but I told them it was fine if they were mixed (as I'm likely to mix them a fair bit myself.)

Media delivered!
Half 1/2" brown river rock and half washed shell
Total 6 ton.

Can't really see much river rock as it was placed in truck firs so is under the shell.