DIYMegaStore.com.au — Pond, Koi & Goldfish Resource Hub

Everything You Need to Build and Maintain a Healthy Fish Pond

Filtration guides, product comparisons, free calculators and care advice for koi and goldfish ponds alike — all in one place.

Expert Guides

Pond Filtration Guides

Filtration is the single biggest factor in a healthy pond — whether you're keeping koi, goldfish, or just enjoying an ornamental water feature, start here to understand your options and set the system up right.

Care & Maintenance

Cleaning, Water Quality & Fish Care

Quick Links

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Free Tools

Pond Calculators

Take the guesswork out of pond planning — size your pump, liner and filter correctly before you buy, whether you're stocking koi, goldfish or both.

View all Pond Calculators →

Help Centre

Pond, Koi & Goldfish Frequently Asked Questions

Quick answers to the questions our pond, koi and goldfish customers ask most.

Planning & Sizing

How do I work out how big my pond filter needs to be?

Start with your pond volume, then size the filter to turn over that volume roughly once every 1–2 hours for ornamental or goldfish ponds, or faster for heavily stocked koi ponds. Use our Pond Volume Calculator to get your litres first, then see our filtration selection guide.

What size pond liner do I need?

Liner size depends on your pond's length, width and depth, plus overlap for edging. Enter your dimensions into our Pond Liner Calculator for an exact size and underlay recommendation.

Do goldfish need less filtration than koi?

Generally yes — goldfish are smaller and produce less waste than koi, so a goldfish pond of the same volume can often run on a slightly smaller filter and pump. That said, goldfish are prolific breeders and populations can grow quickly, so it's worth sizing your filter with some headroom rather than the bare minimum.

Filtration

Do I need a pressure filter or a gravity filter?

Pressure filters can be buried or hidden below pond level and pump water back up under pressure, making them ideal where a gravity-fed box filter isn't practical. See how a pressure filter works and our guide on setting one up.

Do I need a UV clarifier for a koi or goldfish pond?

Yes, generally recommended for both — a UV clarifier controls green water algae by breaking down algae cells as they pass through the filter, keeping water clear for viewing your fish. This matters just as much in a goldfish pond as a koi pond, since both are usually kept for visibility. See our best pond filters guide for models that include one.

Which OASE FiltoClear model do I need?

It depends on your pond volume and fish stocking level — our FiltoClear kit guide breaks down each model and what size pond it suits, whether you're keeping koi, goldfish or a mixed pond.

Cleaning & Water Quality

How do I remove sludge from the bottom of my pond?

A pond vacuum is the most effective way to remove built-up sludge, uneaten food and debris without draining the pond — useful whether you're maintaining a koi pond or a smaller goldfish pond. See our comparison of the PondMAX PV30HD vs OASE PondoVac range, or shop Pond Vacuums.

My pond water has a brown or tea-coloured tinge — what's causing it?

This is usually tannins leaching from timber, leaves or other organic matter, not a sign of poor filtration, and it's just as common in goldfish ponds as koi ponds. Our BBA PurePond range guide covers the specific bacteria treatment for tannin-stained water.

What water treatments does my pond actually need?

It depends on the issue — dechlorinating tap water top-ups, breaking down sludge, clearing green or cloudy water, or controlling string algae all use different products, and the right treatment doesn't really change based on whether you're keeping koi or goldfish. The BBA PurePond guide matches each symptom to the right product, or shop Water Treatments directly.

Koi & Goldfish Care

How often should I feed my koi or goldfish?

Feeding frequency and amount changes with water temperature and season for both species — overfeeding is one of the most common causes of poor water quality in any pond. Goldfish generally need smaller, less frequent feeds than koi given their smaller size. See our full koi feeding guide — most of the seasonal principles apply equally to goldfish.

Ordering Info

Pond Shipping & Delivery

For an exact quote, add items to your cart and use the "Estimate Shipping" tool at checkout. Full details on our Shipping Guide.

Planning a larger or custom pond?

Whether it's a custom-sized koi pond, a goldfish pond for the kids, or a full filtration system, if you'd simply like a second opinion before ordering, email us your design, dimensions or photos and we'll help you put the right setup together — no obligation.

Email: support@diymegastore.com.au — attach your sketch, photo or dimensions and one of our pond specialists will get back to you with recommendations.
Prefer to talk it through? Call 1300 238 288.

Still Have Questions?

Our pond, koi and goldfish experts are ready to help — from filtration selection to installation advice.