Backyard Aquaponics
A place to discuss aquaponics

Just so you know, the ratio is usually thought of as grow bed to tank so for the 2:1 ratio you would want twice as much gravel volume as you have tank, not the other way around. No worries for you so far though as it doesn't sound like you have gotten much spike of anything yet. did you ever have an Ammonia or Nitrite spike?

Yeah I understand the ratio is 2 growbed to 1 tank, or 4 gal growbed:2 gal water:1 lb fish. Since I'm backwards on the growbed to tank I somehow came up with 1 lb per 10 gal of water to 5 gal growbed. When I did the math it made sense but I'm drawing a blank right now lol. I've never had any ammonia or nitrite show up in my water, much less spike.

"When in doubt, add more fish." -- Dave Donley.

I do think your stocking rate is low. More poo would add more nutrients and help bring pH down, too. The nitrogen cycle will naturally lower pH over the long run.

Or as C1 would say ..... just keep on feeding:)

But with limestone as grow bed media, the pH may not come down much, I don't know what pH limestone buffers too. I do know that the shell I have buffers to 7.6 and I won't likely see a pH drop from that until either most of it disolves or I finally get enough stock in the tanks to really push my grow bed capacity to filter and even then I don't know that it will affect my pH much. I've done some wopper doses to the pee ponic system to see if the extra demad on the bacteria would cause any flux on the pH and it didn't.

Was going to suggest that as there are another bank of growbeds to come online ultimately...

Use an "acidic" grow media.... coco-coir would be ideal if it weren't for the fact that it just retains too much moisture in flood and drain IMHO.....

Only other media I can think of is what we refer to and is market over here as "Maidenwell"...

It's a "diatomite"... a amorphous (non crystalline) silica... a naturally occuring, fossilized, mined mineral ....

A diatomaceous earth product similar to that used to absorb oil spoils and/or "kitty litter"...

Don't know if a similar product exist in the US..... this one lists as pH 5.7 - 6.2.....

Would balance the limestone just nicely I reckon....

Only thing I'm not sure of is there would be an almost constant level of high bufferring.... and I suspect a high carbonate hardness level.... brains to numb to figure whether GH or KH tho....

Here's their website for reference.... "The Hopefulls" are using it as a media....

A large number of seedling nurseries and hydroponic operations are using it and raving about it here in OZ...

http://www.maidenwell.com/aboutUs.htm

I LOVE the fact that " samples of all sizes are available".
Think I'll get a 4 cubic metre sample:)

I'm guessing the limestone is either 7.8 or 8.0 because that's where I see my system the most. From google I found:


I'm not totally against replacing my media if that's the best solution, obviously I'd like to avoid this... arf... the washing... the gravel was free... the washing.... I could also hook up a couple more barrel growbeds and fill them with an acid media as well. I don't know if that's a good idea though do ya'll? Acid/Base reaction going on all the time till one finally gets defeated then who knows which way the system will head... ? Also if they weren't balanced would it really do anything or would the acid or base just get overwhelmed?

In the mean time I guess I will increase my stock and do some water changes to help with the algae. I've been catching my own fish for the system, that's why the number of fish has been so low (terrible fisherman), but I've recently discovered a location teaming with sunfish/breem. I had 15 fish in there... caught 1-3 at a time over the course of a few months. The other day I caught 15 in as many minutes! Busted them spawing. I'll let you all know how it goes.

This is research I've done for the International AP Task Team.
pH ranges from 8.7-10 (Calcium Carbonate) CaCO3
Sources include Seashells, Egg Shells, Cuttlebone, Coral, Animal Bones, Limestone Chalk, Marble - Test presence in minerals w/ hydrochloric or sulfuric acid- bubble action

I'd recommend staying away from having 1 acid GB and 1 basic GB. Whatever salt you form through that reaction will build and build and build. Maybe it will precipitate to be dredged out by you, maybe not.

Unless you have a constant supply of lemons or some other mild acid, I think replacing the GB media is your best bet.

And hey, some people don't wash their gravel at all

alrighty fun.. here's my current status. I've done two 33% water changes. Before I started the pH of the water was around 8.0 pH. I drained off 100 gals onto my garden... I know how you aussies can't bear to see us wasting out water here in the states Since the system was 1/3rd low I figured that would be a good time to tackle some of the algae. I misted the exposed algae with 2% hydrogen peroxide (3% hydrogen peroxide from the store with a bit of water added just to make it go further in the spray bottle). I then scrubbed scrubbed scrubbed all the algae free from any surface I could find in the tank. I then refilled with de-chloramined tap water. Before adding the tap water to the system I dosed each 50 gals with 100 mL vinegar (this brings my tap water to 7.0-7.2ish and drops the carbonate hardness to 3). After adding the 50 gallons of pH 7.0 water to the system I figure I'd check the pH... 8.0 on the dot. :/ Ok, water change number 2... drain off another 100 gals (yeah onto my garden...woo hoo) and replace it with 100 gal more of 7.0-7.2 pH water... afterwards I test the pH of the system again.... 8.0. Well, I guess I know what pH my gravel is buffering to. On a side not, the tank looks a lot nicer already without all the algae. I'll do one more water change tomorrow. I might make it down to the lake to catch 15 or so more bluegill to increase stock density.

I priced hydroton (ack, some of you must be wealthy). I guess I need to look for some different gravel. I'm just worried that because of the part of the country I live in everythings going to have limestone, or whatever is causing my problem, in it.

Thanks for all the suggestions. Let me know if you think of anything else. I wonder if it's even worth waiting to see if the increased fish density will make a difference or if it'll just get couteracted by my gravel. I guess either way, the system would be much better off with different gravel.

angie, not looking for a fight or anything, but can you post up the research on the buffering PH's of CaCO3?

All the resorces i've look at quote mid to high 7's for the calcite form and 8 to mid 8's for the aragonite form.

limestone chalk especially will also have magnesium carbonates present

this is also shown empirically by TClynx's system sitting at PH 7.6 and my (and millions of reef keepers) reef tank sitting at ph 8.5 with about 50kgs of aragonite sand.

most sea shells are predominately calcite with a small proportion of aragonite (i believe oyster shells have a higher aragonite component), this also explaine TClynx's system originally peaking at the higher PH of mid 8's.................

that explains why everything is bigger in Texas, tap water avg 8.5 wow

LOL, just a little higher and you wouldn't need soap in the shower! fat + lye = soap

ever wondered why your fingers feel "soapy" if u get a caustic solution on them?