Ponding 101
Welcome to Ponding 101!
Here we discuss many things associated with building and maintaining a pond and/or water garden. This includes Frequently Asked Questions, basic rules of thumb, and conversion charts to help with sizing.
Table of Contents
- Construction Guides (PDF Manuals)
- Calculators & Sizing Tools
- Filtration & Combined Filtration
- Choosing the Right Filter
- Selecting a Pump (Head, Friction, Pipe Size, Waterfall)
- Installing a Pond (Location, Shape, Depth, Liner)
- Sizing Formulas & Volume
- Conversions
- Pipe Size Chart
- Abbreviations
- Fish Stocking & Plant Stocking
- Rocks, Boulders & Gravel
- Waterfall Width Chart
- Frequently Asked Questions
- External Pumps (Flooded vs Non-Flooded Suction)
- Important Disclaimer
Pond, Waterfall, Pond Free Construction Guides
Below are links to construction guides saved as PDF files. Most modern browsers open PDFs directly.
- Atlantic Water Gardens - Pro Series Pond Kit Instructions Manual (PDF)
- Atlantic Water Gardens - Oasis Series Pond Kit Instructions Manual (PDF)
- Atlantic Water Gardens - Waterscapes Pond Kit Instructions Manual (PDF)
- Aquascape - MicroPond Kit Series Installation Manual (PDF)
- EasyPro - Eco Series Pond Kits Brochure (PDF)
- EasyPro - Eco Series Pond Kits Instruction Manual (PDF)
- Savio - LivingPonds Pond Kit Construction Guides (PDF)
- Savio - Pond Free Kit Construction Guides (PDF)
Calculators and Sizing Tools
Explore our calculators and tools designed to simplify selecting the right equipment for your waterfall project: pump sizing at total head height, tubing ID suggestions, liner and underlayment sizing, and pondless reservoir volume.
- Pond Liner and Underlayment Size Calculator
- Waterfall Pump Sizing at Total Head Height Calculator (with tubing ID suggestion)
- Pond Free Reservoir Volume and Reservoir Cube Calculator
Filtration
To appreciate the beauty of a pond, maintenance needs to be easy and the water needs to look clean. An effective filter creates clean and clear water with only a few light cleanings per year. Generally, the smaller the filter, the more maintenance and the poorer the water quality. Greater surface area helps reduce cleaning frequency and improves filtration efficiency.
Filter size requirements vary depending on water temperature, sunlight, stocking capacity, feeding habits, waste loads, cleaning requirements, and local water chemistry. For a low maintenance water garden, a good rule of thumb is for the bio-mechanical filter to hold at least 3%–7% of the total volume of the pond water in the filter.
Combined Filtration is the Best Way to Maintain Consistent Clear Water
Using biological and mechanical filtration is often not enough by itself. Adding a skimmer built into the pond edging can drastically reduce maintenance by removing surface debris before it sinks. Adding an ultraviolet clarifier (UV or UVC) is another part of the filtration system that helps keep water crystal clear by clearing green water.
Avoid getting a pump that is not strong enough. Many pond owners choose a pump one size up from a conservative estimate and add a ball valve after the pump discharge. This allows you to control discharge flow and fine-tune performance. A diverter valve can also be used to send water to two different returns/sources and control flow to each.
Choosing the Right Filter (Which is Right for Me?)
Filters come in many types: biological, mechanical, pressurized, upflow, bead, and more. Below is your original breakdown—reformatted for easier reading, while keeping your key points and product links.
Bio / Gravity Fed Filters
Examples include Tetra Clear Choice Filters and FishMate Biological Filters. These typically sit near the pond edge. Water is pushed from a submersible pump up to the filter inlet, and then spills out by gravity. They often use foam pads and may include (or offer) UV.
Pressurized Filters
Your page notes these are popular because they can be buried about 2/3 into the ground for easier concealment. Since they’re sealed, pressure helps push water to a waterfall/stream. Your guidance recommends refraining from lifting water more than ~3–4 ft of total head lift from the filter to the discharge point. Some models offer backwash features (dial/lever systems) to discharge waste to a garden area.
Upflow Filters (Waterfall Box Style)
Upflow filters are often used in professional installations. Water is pushed up through media and then flows over a waterfall lip (weir), although some models discharge through a 2" pipe instead of over a weir. Your page notes they can be used with submersible or external pumps, and are commonly paired with a skimmer to reduce maintenance (skimmer not required).
Bead Filters (Higher-End Filtration)
Bead filters are commonly used for koi ponds or heavy fish loads. Your page highlights Aqua Ultima II filters, which are easily backwashed. It also notes that when sizing, you may account for resistance through the filter (your page uses a simplified rule of thumb to subtract head for filter resistance).
Selecting a Pump
For healthy filtration, your page recommends a pump strong enough to circulate the total pond volume through the filter about once every 1–2 hours. Your page also notes a minimum starting point of ~500 GPH for basic circulation (always size to your actual pond and system).
Pumps incur resistance as they move water from the pond to the filter, waterfall, or water feature. Output is reduced the farther and higher the pump must push water. Pumps are typically rated at their flow without resistance (always reference pump flow charts for specifics).
Friction diminishes pump performance as water travels through plumbing. Your page uses a rule of thumb that every 10 feet of horizontal travel through pipe is roughly equal to 1 foot of vertical head lift. Avoid too many curves or sharp angles, and do not undersize pipe/tubing to the pump and filter.
Gallons per hour (not the pump discharge diameter) is the way to determine proper pipe size. Many people undersize plumbing and lose optimum pump flow. Proper pipe size is determined by the maximum GPH capacity of the pump. See the pipe size chart below.
For waterfalls, your page uses a rule of thumb of about 1200 GPH per foot of waterfall width as a starting point. Your page also notes that personal preference may warrant higher flow, and that 2400 GPH per foot can create a thicker waterfall sheet. Many pond owners use one pump for filtration flow and a separate pump sized for waterfall aesthetics.
Your page notes that most pumps should be located below the pond surface level (flooded suction) so gravity supplies the pump and helps maintain prime. Some external pumps may be self-priming or require a priming pot/leaf trap to operate above water level.
Helpful information on pond pumps and waterfall pumps
Installing a Pond
Choose a location that is easily viewed and accessed from the home. Avoid placing the pond under pine or fruit-bearing trees. Your page suggests placing the pond where it receives plenty of sun in all seasons, and designing it as a focal point in the landscape.
Natural shapes with smooth curves (jelly bean / kidney bean) are popular. Formal shapes include round, square, and rectangle.
Avoid eccentric shapes with sharp curves and niches. These can allow stagnation and create excessive liner folds where debris can build up.
A common complaint after completion is that the pond is too small. Ponds shrink visually once you add rocks, plants, and landscape. Small ponds can get lost in the landscape. Larger ponds are often easier and less costly to maintain.
In areas with hotter or colder extremes, your page suggests considering no less than 3–5 feet. In general, a good minimum pond depth ranges from 2–5 feet. Deeper ponds lose less water to evaporation, remain more stable, and support fish better over winter. Always allow plant ledges and keep safety in mind with small children.
A non-woven GeoTextile underlayment can add protection under the liner and help with moisture and gases under the liner. GeoTextile can also be used on top of the liner when placing larger or sharp rocks/boulders.
This is the foundation of your pond. Choose a fish-safe liner made for ponds with strong reputation and warranty support, such as Firestone PondGard. Your page notes a commonly cited service life of many decades when properly installed. Avoid roofing liners or liners not manufactured for fish-safe pond use.
Sizing Formulas
Maximum width, maximum length, maximum depth. Multiply maximum depth by 2. Add 2 feet for overhang (1 foot each side × 2). Add that total to maximum width and add the same total to maximum length. Round up to match pre-cut liner sizes.
Example (your example): Max width 5', max length 10', max depth 2.5'.
(2 × 2.5 = 5) + 2 = 7. Then (7 + 5 = 12' width) and (7 + 10 = 17' length).
Closest would be 15' × 20' (or re-measure after backfill to see if 10' × 15' works).
Rectangular pond: Length × Width × Depth × 7.5 = Gallons
Round pond: 3.14 × r2 × Depth × 7.5 = Gallons
(r2 = half pond diameter times itself)
Natural ponds: Length × Width × 0.8 × Depth × 7.5 = Gallons
(0.8 compensates for lack of corners; use 0.85 for ponds 400+ square feet)
Conversions (your chart)
| 1 Teaspoon | ~5 ml |
| Drops per teaspoon | 100 |
| 1 Tablespoon | ~15 ml |
| Teaspoons per Tablespoon | 3 |
| 1 US Gallon | 3.78 L |
| 8 oz in a cup | |
| 2 Tablespoons per ounce | |
| 16 oz in a pint | 16 cups in a gallon |
| 32 oz in a quart | 1/8th = 0.12 HP |
| 128 oz in a gallon | 1/6th = 0.14 HP |
| 1 gallon of water weighs | about 8 lbs |
| 1/4th | 0.25 HP |
| Watts | = Amps × Volts |
| Volts × Amps | = Watts |
Pipe Size (your guidance + chart)
Undersized pipe restricts optimum water flow. Never select pipe size based on the pump discharge size. Pipe sizing should be selected based on the gallons per hour/minute of the pump. Your page adds: for every 25 feet of pipe run, increase pipe size by 1/2" diameter (rule of thumb).
| Pump GPH | PVC Pipe ID |
|---|---|
| 0–70 | 1/4" |
| 0–150 | 3/8" |
| 0–300 | 1/2" |
| 300–700 | 3/4" |
| 700–1200 | 1" |
| 1200–2200 | 1-1/4" |
| 2200–3500 | 1-1/2" |
| 3500–4800 | 2" |
| 4800–9000 | 3" |
| 9000–12000 | 4" |
Abbreviations (your list)
GPH = U.S. Gallons Per Hour
GPM = U.S. Gallons Per Minute
FPT = Female Pipe Thread
MPT = Male Pipe Thread
FNPT = Female National Pipe Thread
MNPT = Male National Pipe Thread
S = In fittings: Slip / Solvent end
SPG = Spigot (same outside diameter as Schedule 40 PVC pipe)
Stocking Guidance (your rules of thumb)
1 adult koi per 10 square feet of pond surface area, or 1 adult goldfish per 2 square feet of pond surface area (consider average fish size).
Rule of thumb: For a well filtered pond, 10 inches of koi per 100 gallons of pond water.
We recommend starting with 1/2 the maximum stocking to allow for fish growth and reproduction.
1 mature lily per 15–20 square feet of surface area. Place as many bog plants as desired. If fish are present, cover no more than 70% of total pond surface area with plants and have no more than one 1-gallon pot of oxygenators per 500 gallons of pond water.
Rocks and Boulders (your formulas)
Quantity (approx.) of rocks to use in a 2 foot deep pond:
Length × Width ÷ 65 = Qty. of boulders used in the pond (tons)
Example: 10 ft × 5 ft ÷ 65 = 0.77 tons of boulders
Quantity of 1/2" to 3" gravel to use in pond:
Multiply the qty. of boulders (tons) × 0.45
Example: 0.77 × 0.45 = 0.35 tons of gravel
Quantity of boulders to use in a stream:
1/2 ton per 10 ft of stream length
Quantity of 1/2" to 3" gravel used in the stream:
1/2 ton per 10 ft of stream length
Boulders for Facing:
Approximately 1/2 to 1-1/2 tons of boulder around the face of your biological filter
Waterfall Width Chart (your chart)
| Width of Weir (GPH per ft) | Smooth Weir (Thickness) | Stone/Rough Weir (Thickness) |
|---|---|---|
| 360 | 1/4" | 3/16" |
| 600 | 3/8" | 5/16" |
| 900 | 1/2" | 3/8" |
| 1680 | 3/4" | 9/16" |
| 2400 | 1" | 3/4" |
| 4500 | 1" | 1-1/4" |
| 6720 | 2" | 1-3/4" |
For streams where the water is not sheeting but rather flowing gently, your page suggests using about 1/2 of the GPH recommended above.
Some Common Frequently Asked Questions
Do I need a filter?
If you desire a clear pond you should install a filter. Your page recommends two filters for water gardens: a mechanical skimmer filter to protect/hide the pump and skim dust & debris, and a biological filter to keep water clear and safe for fish (up-flow, pressurized, or gravity fed).
How often should I clean my filter?
Mechanical filters should be cleaned whenever they slow flow to the pump. Smaller in-pond filters may require frequent cleaning. Out-of-pond skimmers are commonly cleaned about once a week (often just a few minutes to empty the net and rinse mats). Biological filters should generally only be cleaned if water flow is diminished. Large up-flow waterfall style biological filters are commonly cleaned about once per year (per your guidance).
Do I have to add fish?
No, but fish do eat mosquitoes and are recommended. Fish can help with mosquito control, add life and color, and can be trained to eat out of your hand.
Do I need a bottom drain?
Bottom drains promote better pond water recirculation through filters. Your page notes they are a must for koi ponds and recommended for water gardens over 3 feet deep or more than 2000 gallons. They can be added easily with an out-of-pond skimmer or attached to the intake of an external pump. Your guidance recommends attaching a bottom drain direct to an external pump for stronger draw.
I have green water… how do I get rid of it?
Your page lists three approaches: (1) balance the pond, (2) chemical additives such as AlgaeFix, and (3) an Ultraviolet Clarifier (UVC). Shading (especially with plants) can help. Water tints such as Bio Blue are another option. Your page also advises avoiding drastic tap water additions; add water in small amounts and treat with a chloramine neutralizer.
Why is my waterfall weak even with a high-GPH pump?
Your page explains that pumps are rated at low/no resistance and flow decreases with head pressure and friction loss. Measure vertical lift and consider friction losses (pipe length, fittings, undersized pipe). Use the pipe size chart and waterfall width chart as starting points.
Should I use one pump or two pumps?
Your page notes some pond owners use two pumps: one sized for filtration flow and a second sized for waterfall aesthetics (example given: filtration may need 500–1000 GPH while a 3-foot waterfall may start around 3600 GPH or higher based on preference).
How do I choose tubing/pipe size if my pump outlet is smaller?
Your guidance: don’t size pipe based on the pump discharge diameter. Size pipe based on the pump’s GPH and the plumbing run, because undersized pipe restricts optimum flow.
How often should I clean biological media?
Your page recommends not cleaning biological filters unless they are so blocked that water flow is diminished. (Mechanical capture components are cleaned when they reduce flow.)
What’s the fastest way to reduce pond maintenance?
Your page emphasizes combined filtration. Skimming removes debris before it sinks and breaks down, which can greatly reduce bottom waste and maintenance.
External Pumps
Your page guidance: locate the pump as close to the source as possible and keep the main (longest) run of pipe on the discharge side. The pump is designed to push water, not pull it.
Flooded Suction (your diagram + guidance)
1. Locate the pump as close to the source as possible. It is best to have your main (longest) run of pipe on the discharge side of the pump. The pump is designed to push water, not pull it.
2. Install the pump outside the pond, and if possible below the level of the pond surface (flooded suction). This helps ensure a proper supply of water. Even if the supply line comes up and over the pond wall, it can still be flooded suction if there are no breaks to atmosphere before it drops below water level again and all air is removed.
Non-Flooded Suction (your diagram + checklist)
3. If it is not possible to provide a flooded suction installation then:
- A. Position the pump as low as possible and as near the source as possible.
- B. Install a basket strainer on the inlet of the pump or provide another priming source.
- C. Suction piping should slope gently upward to the pump or strainer inlet.
- D. Install a foot valve or a check valve in the inlet line below the water level.
- E. Always prime the entire inlet line, basket strainer, and pump before turning it on.
- F. If your pipe has a high spot, install a tee at the highest spot to prime/bleed air.
Important Disclaimer (your wording kept)
The above information is used for guideline purposes only and should be verified with a professional before proceeding.
Safety should always be a #1 concern.
We will not be liable for any damages caused by misuse or mishandling or any harm caused by the information that we provide above.
This information is free to use by our customers as a tool in assisting them to purchase our products and problem solve. Others please do not take our information as it is considered theft. If you would like to use the information above on your website or in print, please submit this to us in writing. Copyright 1999-2026 - Jolie Products Inc DBA 123Ponds.com
Recommended Starting Points (Fast Links)
Use these pages when you’re actively sizing a build or troubleshooting performance.
DIY Pond Kits (Keep These Links)
If you want a proven set of components sized to work together, start with pond kits.
Skimmer Link Standardized
Per your instruction, any skimmer link on this page points to: https://www.123ponds.com/skimmers.html
Quick Tip: Two Biggest Flow Killers
- Undersized plumbing (size pipe by GPH, not by pump outlet).
- Too many tight fittings / long runs increasing friction loss.
