Stock Tank Pool Setup: Filter, Pump and Heater
A stock tank pool needs a filter pump that can move the tank's water through the filter at least once a day, plus two sealed holes in the tank wall for hoses. Behlen's 2 ft deep round tanks hold about 389 gallons (6 ft), 706 gallons (8 ft) and 1,117 gallons (10 ft), and a 300 gal/h pump filters even the 10 ft tank once in under 4 hours.
Always follow your product’s label directions. Pool and spa chlorine, bromine, shock and algaecides are EPA-registered pesticides: use products labeled for pool or spa use, and don’t swim or soak until levels are within the limit on your product’s label. If this page and a label disagree, the label wins.
On this page (7 sections)
This page covers the equipment: tank, pump, filter, hoses, and an optional heater. Chlorine doses, rust, and green water are on the stock tank pool chemicals page.
Pick the tank: maker's gallons
Tank makers rate their tanks by "approximate" gallons. Behlen Country, a common stock tank maker, publishes these for its round galvanized (zinc-coated steel) tanks. We list our own calculated full-to-the-rim volume beside them, from the stock tank pool page.
| Tank | Behlen capacity | Height | Our calculation (full to rim) | Drain plug listed |
|---|---|---|---|---|
| 3 ft × 2 ft | 85 gal | 24 in | not calculated | Yes |
| 4 ft × 2 ft | 165 gal | 24 in | not calculated | Yes |
| 6 ft × 2 ft | 389 gal | 23.5 in | 423 gal | Not listed |
| 8 ft × 2 ft | 706 gal | 23.5 in | 752 gal | Not listed |
| 10 ft × 2 ft | 1,117 gal | 23.5 in | 1,175 gal | Not listed |
Behlen lists several diameters (for example 89, 92.5 and 96 in for the 8 ft size), so the same item number comes in slightly different shapes. Use the maker's number as your starting point, then lower it for how high you fill. Your own tank may differ.
Your tank is not usually filled to the rim. A tank filled 3 in below the rim holds less than either figure, so the hours below are slightly shorter than shown. If you want to size from the real water depth, use the round pool volume calculator.
Pick the pump: how fast it turns the water over
For pools, Intex support advises filtering the whole volume once a day, usually 6 to 8 hours, and no more than 8 hours a day. For a tank, the formula is the same: hours per turnover = tank gallons ÷ system flow (gal/h). Use the system flow, which Intex gives as 300 gal/h for the C330 pump and 475 gal/h for the C530. The C330 page says it suits pools up to 2,400 gallons.
| Tank | Intex C330 (300 gal/h) | Intex C530 (475 gal/h) |
|---|---|---|
| 85 gal | 0.3 h | 0.2 h |
| 165 gal | 0.6 h | 0.3 h |
| 389 gal | 1.3 h | 0.8 h |
| 706 gal | 2.4 h | 1.5 h |
| 1,117 gal | 3.7 h | 2.4 h |
Both pumps pass the biggest tank once in under 4 hours, so either one can cover a stock tank. The larger pump turns the water over faster. Intex's pump pages list the C330 as using Type H cartridges and the C530 Type A. See the Intex pump guide for the full model list.
Bestway's pumps are rated for pools from 300 gallons upward (for example 300–5,100 gallons for its 1,000 gal/h pump), so they do not list the 85 and 165 gallon tanks. Intex's C330 page gives only a maximum. If your tank holds under about 300 gallons and you do not want a filter, treat it as a kiddie pool: kiddie pool chlorine explains why emptying often is easier. The pump run time calculator turns your own numbers into hours.
Cartridge or sand?
For tanks under about 1,200 gallons, a cartridge pump is the simpler choice: no backwashing, and you rinse or swap the cartridge. Intex support says cartridge filters suit smaller pools and sand filters suit larger ones. Intex's smallest sand model we checked, the SX1500, is rated for 2,800 to 8,400 gallons, so every stock tank above is below its listed range. DIY guides, which are not maker sources, say people often use Intex sand filters on stock tanks anyway. We did not test that.
Hoses and holes in the tank
A stock tank has no skimmer or return fitting, so you add them. The usual set-up has two bulkhead fittings (a threaded fitting that seals through a hole with gaskets). One DIY guide places the return (water going back into the tank) near the top, just under the water line, and the intake near the bottom. Intex cartridge pumps listed above use 1.25 in (32 mm) hose fittings, so choose bulkheads and adapters that match your pump's hose size.
- Choose where the pump will sit. Keep it dry, on level ground, and away from the tank so children cannot climb on it.
- Mark the two holes and drill them with a hole saw the size your bulkhead fittings call for.
- Smooth the cut edges with a metal file. On a galvanized tank, the cut exposes bare steel, so cover the edge with rust-resistant paint or sealant before fitting the bulkheads.
- Fit the bulkheads with their gaskets and O-rings, tighten them, and connect the hoses with clamps.
- Fill the tank above the top fitting. Open the pump's air release valve and let air escape until water flows out of it, then close it. This is the same air step Intex describes in its manual.
- Look for leaks for the first day. If a fitting leaks, check the gaskets and O-rings first, then tighten it again. A DIY guide says caulk is a last resort.
The step about painting the cut edge is our advice from how zinc coating works, not a maker's instruction. Behlen's tanks have a zinc coating, and a cut removes it at that spot. Rust often starts at such places, as the stock tank chemicals page explains.
Heater: making it a stock tank hot tub
A pool-sized pump does not heat the water. For warm water, owners add a heater in the return line, after the filter. We did not find a maker's guide for stock tank heaters, so the figures below are the claims of one seller of propane outdoor water heaters (stocktankpool.net), not tested by us:
- A 41,000 BTU/hr heater adds about 5 °F per hour to an 8 ft tank.
- A 68,000 BTU/hr heater adds about 10 °F per hour. The seller says this takes an 8 ft tank from 60 °F to 90 °F in about 3 hours.
- A 110,000 BTU/hr heater is claimed to take a tank from 50 °F to 100 °F in as little as 2 hours.
Before you buy anything, read the heater maker's manual for where it may be mounted, how it must be vented, and whether it can be used outdoors. The seller's page says to mount the heater on something sturdy such as the side of a house or a fence, and not to mount anything above its exhaust pipe. Gas heaters give off carbon monoxide, and electric heaters need a GFCI outlet.
Keep a hot tub at 104 °F or lower, the limit set by the U.S. Consumer Product Safety Commission. The CDC recommends not using cyanuric acid, or chlorine products that contain it, in hot tubs. We have no test data on how galvanized steel holds up in hot, chlorinated water, so check the tank often. For hot water chemistry, see hot tub chlorine and the hot tub chemical calculator. To size or cost a heater for your volume, try the pool heater size calculator.
Safety
A stock tank is deep enough for a child to drown in. Supervise all swimming, and cover or fence the tank when it is not in use. Plug the pump into a GFCI outlet, and keep the cord and outlet away from the tank edge. Never mix chlorine and acid. Always follow the product label.
FAQ
Does a stock tank pool need a filter and pump?
If you keep the water more than a day, yes. A filter pump circulates the water so chlorine can reach it and the filter can clear debris. Without one, empty and refill.
What size pump for a stock tank pool?
Divide the tank's gallons by the pump's system flow to get hours per turnover. Intex support says to filter the whole volume once a day. An Intex C330 (300 gal/h) does that for a 1,117 gallon tank in about 3.7 hours.
How do you plumb a stock tank pool?
Drill two holes, fit a bulkhead fitting in each, and connect the pump's hoses with clamps: return near the top, intake near the bottom. Seal and coat the cut edges on a galvanized tank.
Can you heat a stock tank pool?
Yes. Owners plumb a heater into the return line. We have no tested figures, only a seller's claims, so follow the heater's own manual and keep the water at 104 °F or lower.
How many gallons are in a stock tank pool?
Behlen lists 85, 165, 389, 706 and 1,117 gallons for its 3, 4, 6, 8 and 10 ft round tanks. Other makers may differ, so check your tank's own rating.
Sources
- Behlen Country, Farmstead round stock tanks (capacities, heights, drain plugs): behlencountry.com
- Intex, C330 Krystal Clear cartridge filter pump (300 gal/h system flow, up to 2,400 gal): intexcorp.com
- Intex, C530 cartridge filter pump (475 gal/h system flow): intexcorp.com
- Intex, SX1500 sand filter pump (2,800 to 8,400 gal): intexcorp.com
- Intex Support, How often should the filter pump be used: intexsupport.com
- Intex Support, Choosing a pool filter: intexsupport.com
- Bestway USA, 1,000 gal. filter pump (pool range 300–5,100 gal): bestwayusa.com
- DIY guide, Poolonomics (hole placement, filing edges; not a maker source): poolonomics.com
- Seller page, Stock Tank Hot Tub propane heaters (heating rates, not tested by us): stocktankpool.net
- CDC, Home pool and hot tub water treatment and testing (no CYA in hot tubs): cdc.gov
- U.S. Consumer Product Safety Commission, hot tub temperatures: cpsc.gov