FAQ #32: Where should I direct my pumps flow – the tank’s rock work, or the surface of the water?

FAQ #32: Where should I direct my pumps flow – the tank’s rock work, or the surface of the water?


Today on the 52 FAQ we’re going with the flow. Hi, I’m RT your host of BRSTV’s 52 FAQ
where we answer all kinds of reefing questions from our popular series 52 weeks of reefing. Today we’re answering Yeshwanth Yarremsetty’s
question, “Should I keep flow directed towards my rock work, or slightly upwards to create
waves on surface?” If at all possible, I’d recommend both. It’s important to have surface agitation in
the aquarium as this promotes gas exchange. In other words, carbon dioxide is gassed out
of the tank resulting in a higher pH from a lower concentration of CO2 and carbonic
acid in the aquarium, and potentially lower nitrates as anaerobic bacteria convert nitrate
into nitrogen gas that then gasses out of the aquarium. Adequate surface agitation helps to make these
processes much more efficient. The other component to this is oxygen entering
the aquarium. The rippling surface of the water helps to
bring more oxygen into the aquarium. Not only is this important for your corals
and fish ability to respire, but it also helps to displace those gasses I mentioned earlier:
CO2 and Nitrogen. Additionally, increasing your surface agitation
can increase your evaporation rate. If your tank is running warm, a higher evaporation
rate is a good thing to shoot for. As the water evaporates it takes heat away
from the water. Coupling that with a fan pointed at the water’s
surface can increase the impact of this effect, and in some cases can drop temps by 2 degrees
or more depending on the situation, potentially even eliminating the need for a chiller. Why then should flow also hit you rock? It’s simple. Your rock and sand like to trap and hold many
unwanted elements such as detritus, left over food, and fish waste. These are often referred to as dead spots,
where flow doesn’t reach, and waste builds up. If not removed, they can all break down into
nitrate and phosphate and fuel algae growth in your aquarium. The flow from your pumps will help keep these
partials suspended in the water column to be removed by your filter sock, roller matt,
and skimmer before they have a chance to break down further. So what If one pump can’t do both? You might try adding a second, or use one
of a different style like the Maxspect gyre whose unique flow pattern is better suited
for complex flow patterns. I might also try to re-aim or re-position
my pumps to temporarily to stir the sand, rock and tank. Additionally, controllable pumps offer the
ability to create random and chaotic flow patterns that can help eliminate dead spots
in the tank. That said, all of this needs to work with
your coral needs first. Some corals like many acropora love high flow,
where as some LPS like Scolymia or acanthophylia can be stressed by too much flow. Find the best flow for them, then try to adapt
your setup to achieve these other goals. If you are interested in learning more about
Flow do yourself a favor and checkout Week 9 of 52 weeks of reefing Why flow is vital
for a successful reef tank. Don’t forget answering your questions is what
the 52 FAQ is all about on so ask us something you want to know in the comments area below. See you soon with the next 52 FAQ.

37 thoughts on “FAQ #32: Where should I direct my pumps flow – the tank’s rock work, or the surface of the water?

  1. @BulkReefSupplyCom I have digitate hydroids all over my aquarium. I have been unsuccessful at finding out how serious the dangers of these hitchhiker are. What is the best course of action for removing them ?

  2. I have my pumps facing away from the surface because it keeps my co2 intake from the surrounding atmosphere of my living room down to a minimum. Which helps increase my ph by a couple decimals.

  3. Always at surface of water column,the only place gas exchange can occur. If more flow is needed,additional circulation pumps can be added

  4. I've got two Sicce Voyager 2 units on a wavemaker running along the top of my 65 gallon tank. Looking into adding two lighter powerheads for the back, how much flow should I be looking for?

  5. BRS my house is on a septic tank. Can u plz make a vid on ways I can do water changes by not using drains
    ??? I have a drain outside my house for floods which isn't on the septic tank. Would it work if I just ran a gravel vac line about 150 plus feet to the drain? Thanks!

  6. Brs I have a question on how would you hang a ocean revive T247 light I can't hang it from the ceiling and would like to hang it from the tank somehow, do you guys have an item or something that would do that?

  7. hate BRS team you should check my review on you it is really good you might like it was said about you guys so peace out

  8. I guess I don't have the best flow in my tank, did not clean my rocks for a long time and that caused my nitrites to go high

  9. Thanks for the info. I find it really difficult to direct my fans anywhere other than on the surface because of potential agitation of corals. At least I learned about the importance of flow all over the tank though.

  10. is a hydor koralia 425 too much in a 10g nano for a softy/lps tank? i bought one before i knew much about flow. will aiming it at the surface help reduce the flow around the rock work? i have a 125gph hob filter i can use for flow for a bit if the hydor is too much.

  11. @BRSTV… How to find out best/correct size and how many powerheads/wavemakers for different size tanks???
    please and thank you.

  12. My tank size is 24x15x24(inches)-37 Gallon.Is it safe to use 3000L/hr wavemaker keeping neon tetra, rasbora, rummy nose, glowlight, along with clown loaches??

  13. what do u do when u have a dead spot in the aquarium where poop or left food like to stay there.. i've seen some ppl got midle or the opposite of the pump which is water flow cant reach,in my case the dead spot is near the filter.. here some short vid i made and need some advice https://youtu.be/igYMMqDE9HY

  14. Would you recommend a power head for my 65 gallon salt tank or two instead of one. It’ll be just for my fish because I don’t have any live rocks, corals or reefs at this time. But if it will benefit my fish and tank, I want them. Thanks

  15. I have 48 gallon as of now i only have 1 powerhead facing top of the water. Should i get one and direct it to the middle part of my tank. Thanks

  16. Man, i must of drank one strong ass beer because this guy doesn't seem to be speaking english. right after he says "in other words"….he switched gears. lol

  17. I have two Nero 5’s in my 90 gal, and I’m having algae problems in my sand. Anyone have advice for positioning?

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