Welcome back to BRStv Help Desk, where we take common reefing questions and give you straightforward answers. In this episode, we are covering frozen fish food, moving old sand into a new tank, choosing between two larger powerheads or four smaller ones, and figuring out how big your sump really needs to be.

Do I Need to Feed Frozen Fish Food?

The short answer is no. You don't have to feed frozen fish food to have healthy fish.

Instead of looking at fish food as frozen vs. freeze-dried vs. pellet vs. flake, it is more helpful to think about what the fish naturally eats and which food types best match that diet. Some fish are happy to eat just about anything, while others are more specialized and may need a little more variety, a different texture, or a more natural feeding response to do well.

Food Type Pros Cons Best Used For
Frozen Food Natural texture, great variety, often very appealing to picky fish Needs freezer storage, can be messier, usually less convenient than dry food Picky eaters, newly introduced fish, variety feeding, and fish that prefer meaty foods
Freeze-Dried Food Shelf-stable, easy to store, adds variety without needing a freezer Often best when soaked before feeding, may be less appealing than frozen food Occasional variety, treats, and reefers who want easy storage
Pellets Convenient, easy to portion, widely available, great as a daily staple Not every fish accepts pellets right away, and quality varies by brand/formula Daily feeding, automatic feeders, and fish already trained to eat prepared foods
Flake Food Easy to feed, good for small fish, spreads through the water column quickly Can break apart quickly, may be easier to overfeed, and is not ideal for every feeding style Small community fish, surface/mid-water feeders, and quick supplemental feedings
Live Food Triggers strong feeding responses, very natural, useful for difficult feeders More expensive, less convenient, limited availability, and may require special storage or culture Finicky fish, mandarins, pipefish, seahorses, and new additions or reluctant feeders

In some cases, frozen food is simply the best choice. Fish like finicky wrasses, butterflyfish, anthias, mandarins, or other more selective feeders may respond much better to frozen mysis, brine shrimp, copepods, fish eggs, clam, or mixed frozen preparations than they do to dry foods alone.

Frozen food also does not have to be part of your daily feeding routine to be useful. It can be used as a tool to entice picky eaters, help newly introduced fish start feeding in your aquarium, or add variety to a pellet-based diet.

There are also different types of frozen foods. Some are single-ingredient foods like mysis shrimp, brine shrimp, krill, clam, or copepods. Others are blended formulas that combine multiple ingredients into one food, often designed for community reef tanks or specific feeding needs.

Learn More: Saltwater Fish Food Guide: Nutrition, Feeding & Food Types

Do I Transfer Any of My Sand to a New Reef Tank?

The answer to this question is typically no.

While sand beds are good as a home for millions of beneficial bacteria for our aquariums, old sand beds are also really good at holding on to detritus, leftover fish food, and fish waste.

Good Idea

  • Start with fresh sand
  • Add a cup or two of clean established sand
  • Use clean live rock or established media
  • Bring over biology in small, controlled ways

Bad Idea

  • Move the entire old sand bed
  • Disturb deep, dirty sand layers
  • Transfer trapped detritus into the new tank
  • Import unnecessary old tank buildup

With the relatively low cost of new sand, it usually makes the most sense to start fresh when setting up a new tank. Then seed the tank's biological filtration by using a bacterial additive or using just a small amount of sand from a healthy, well-maintained tank. Biological filter media from an established system is another great alternative.

Learn More: Live Sand & Your Reef Tank - What You NEED to Know!

Are Two Bigger Powerheads Better Than Four Smaller Ones?

The answer to this question isn't cut and dry because it'll depend on your tank's dimensions, your aquascape, and what types of corals you're planning to keep.

Using fewer, more powerful powerheads is the most simple option with two powerheads (one on each end of the tank) being the most common configuration. This means fewer cords in the tank, fewer pumps to clean, and an overall cleaner look to your aquarium.

If those two pumps can create the kind of broad, variable flow your tank needs, that is a really solid way to go.

However, four smaller powerheads give you more control. You can attack dead spots from more angles, fine-tune flow around rockwork, and get more targeted movement in tanks with big branching SPS corals or complicated aquascapes.

There is also a point where more pumps just means more clutter, more maintenance, and more equipment in the display without necessarily making the flow any better.

Powerhead Setup Best For Trade-Off
Two larger powerheads Cleaner, simpler setups where two pumps can provide enough broad flow Less ability to target specific dead spots or complex areas around rockwork
Four smaller powerheads Larger tanks, complicated aquascapes, or tanks with obvious dead zones More equipment in the display, more cords, and more pumps to maintain

If your tank can get the flow it needs from two pumps, strongly consider starting there. It is cleaner, simpler, and easier to live with.

If your aquascape is complicated, you have obvious dead zones, or you are trying to create more nuanced flow across a larger tank, then adding more smaller pumps can absolutely make sense.

Tip: Controllable powerheads give you flexibility vs. simple on/off powerheads with no ability to tune the flow rate or pattern.

How Big of a Sump Do I Need?

Let's start by answering the question: What is a sump's main purpose?

At its core, a sump is simply an extra box of water connected to the aquarium. Water drains from the display tank into the sump, passes through the filtration and life support equipment, and is then pumped back up into the aquarium.

The biggest benefit is that a sump gives you a dedicated place to hide and organize equipment that would otherwise need to sit in or hang on the display tank. Protein skimmers, heaters, filter socks or fleece rollers, probes, dosing lines, reactors, refugiums, and return pumps can all live underneath the tank instead of cluttering up the aquarium itself.

So when you're asking how big of a sump you need, you're really asking how much room you need for equipment, maintenance, water movement, and safety margin when the return pump shuts off.

Power Outages and Sump Selection

Be sure to select a sump that is large enough to hold any extra water that flows from the display tank during a power outage. While check valves can help stop this backflow to an extent, you should never fully rely on a check valve to stop your sump from overflowing.

Equipment Space

Make sure the sump can fit the gear you actually plan to run, including your skimmer, heaters, probes, dosing lines, reactors, filter rollers, or refugium equipment.

Water Volume Capacity

Your sump needs enough empty space to safely hold the water that drains back from the display when the return pump shuts off.

Room to Work

A sump that is packed wall to wall is harder to maintain. Extra space makes cleaning, adjustments, and future upgrades much easier.

Tip: Don't completely fill your stand with your sump. Leave a little extra room for electrical equipment like power bars, controllers, and other accessories you don't want getting wet.