Aquaponics Enquiries: Why We Say No More Often Than Yes
Reading this because you are specifying, buying or selling containers? Send the details and a grader answers in writing, usually the same business day.
A stocked aquatic system is the least forgiving application for a reused bottle, because fish respond to surfactant residues at parts-per-million and HDPE releases absorbed residue over months. We quote documented food grade or rebottled only, and lose roughly half of those enquiries.
Aquaponics enquiries come in waves, mostly February to May. They are among my favourite emails to receive and among the least satisfying to answer, because about two thirds of them ask for the cheapest tote on the yard and the answer has to be no.
What the enquiry usually says
A version of: "I'm building a small aquaponics system, I need two 275 gallon totes, what's your cheapest option?"
Entirely reasonable question. The person is building a first system, the budget is their own, and the internet is full of builds using whatever tote was available. Our cheapest option is technical grade at $95 to $145 and it is physically identical in every respect a reasonable person would check.
Why the answer is no
High-density polyethylene is semi-permeable. Over months in service, molecules from the stored product diffuse into the polymer wall. A wash cleans the surface; it cannot reach the bulk. Then, slowly, the wall releases what it absorbed back into whatever is in the tank now.
Fish respond to surfactant residues at parts-per-million concentrations — gill function and the mucus layer are directly affected. And the release happens over weeks to months, not hours.
So the failure sequence runs: fill, cycle for five weeks, stock, plant, succeed for a month, then lose the stock in week six while every water test you can run comes back normal. By then nobody suspects the tank. They suspect the feed, the pump, the weather, themselves.
A container that killed fish on day two would be a cheap lesson. One that does it in week six is not.
What we quote instead
| Option | Price | Our position |
|---|---|---|
| Technical grade | $95 – $145 | Declined for stocked systems |
| Grade A, non-food prior content | $155 – $225 | Declined for stocked systems |
| Grade A, documented edible prior content | = food grade | Yes |
| Food grade, with wash certificate | $225 – $340 | Yes — our usual recommendation |
| Rebottled, new virgin bladder | $340 – $430 | Yes — when food-grade stock is short |
So the honest quote on a two-tote system is around $560 for food grade rather than around $240 for technical. That is a real difference to somebody building in their own garden, and I understand why it lands badly.
What it costs us
Roughly half of those enquiries go elsewhere. Somebody will sell a technical-grade tote to anyone who asks, and from the buyer's point of view they are getting the same object for 40% of the price from a seller who did not lecture them.
We are not claiming virtue here. We decline these partly because it is the right answer and partly because the complaint, if it comes, is unanswerable: the customer did everything right, the tote was as described, and the system died anyway.
The one case where we say yes to technical grade
Hydroponics with no fish, no edible crop surface contact, and a recirculating nutrient solution that gets dumped and replaced on a schedule.
Plants in a flowing nutrient solution are far more tolerant than fish in a closed water column, and a solution that is replaced every few weeks never reaches equilibrium with the wall. If you are running lettuce in NFT channels with a technical-grade reservoir that gets emptied monthly, that is a defensible build and we will quote it.
Add fish, or grow something whose edible part sits in the water, and we are back to food grade.
How to spend less without taking the risk
Three legitimate routes, in order of how much they save.
- Use a technical-grade tote for the sump or the header tank and a food-grade one for the fish tank. The sump is in the water circuit, so this only works if it is in series with a large food-grade volume and the solution turns over — ask us, it depends on the build.
- Buy one food-grade tote and make your media bed from a cage-only frame with a liner. The grow bed does not need a bottle at all, and a cage planter frame is $35 to $60.
- Ask for staining. A heavily dye-stained food-grade unit is at the bottom of the band — $225 rather than $340 — and the staining is purely cosmetic. It will be pink. The fish do not mind.
That third one is the most useful and the least obvious. Cosmetic condition within a grade carries a real price spread and no functional difference.
780 words · published 5 August 2025 by Dale Prichard, Senior grader at IBC Tote Market LLC. We correct posts rather than quietly deleting them; if something here is wrong, tell us and we will say what changed.