Lava rock for sump
- Thread starter monsterK
- Start date
Yup just normal lava rock. It's great due to it being so poris. Lots of beneficial bacteria growing area. Break up the bigger pieces into smaller ones to increase the available growth area.
Ok awesome I plan on putting alot in mesh bags so if I need to clean something I can remove it easily. Do you suggest just throwing them on the bottom or should I prob them up off the bottom of the sump so it doesn't suffocate the bottom of the rocks
I have been using pumice for twenty plus years. I swear by it.
From experience, I do not just throw it in, I keep it in mesh bags, and keep the bags about half an inch off the bottom surface.
The pumice does not get clogged up, and there is no persistent mess of pumice dust on the floor.
I do clean the pumice, every two years. That is enough. One at a time, over a series of weeks, I take a mesh bag out and give it a quick rinse.
From experience, I do not just throw it in, I keep it in mesh bags, and keep the bags about half an inch off the bottom surface.
The pumice does not get clogged up, and there is no persistent mess of pumice dust on the floor.
I do clean the pumice, every two years. That is enough. One at a time, over a series of weeks, I take a mesh bag out and give it a quick rinse.
I am so glad someone else also just rinses.
I was told so many times, you have to take it out, put it in a pot. Boil it for X amount of time to clean it properly to clear all pores etc. 18+ years of rinsing in straight tap water and no issues.
I was told the tap water will get trapped in pores, and chlorine leaks back into the tank. Etc etc. With our water supply here, we are so lucky. Fish breed in straight tap water with no conditioner. I have not used conditioner in years.
But to answer OP. Anything porous and lightweight is a step in the right direction. I use lava rocks ranging in size from about 1/2 a penny (1 cent piece) to dollar sized ( about 2" long). They all do the same thing and keep the water clean. I rinse sumps out about every 2-3 years as well as Midwater mentioned. Although I just rinse the whole sump not individual bags. The amount of tanks and decor connected to my sump means the media re-seeds really quickly and effectively. Having the big emersed plants does hurt either.
Lava rock is a great biological filtration medium. However, I highly recommend buying it locally or from a reputable aquarium store online. Why? Because lava rock can come from very different sources, and not all of them are safe to use straight in a filter — whether it’s a canister filter or a sump.
Some lava rocks may contain heavy metals or other contaminants that can leach into the water and harm your fish. I’m not suggesting you need to buy branded options like EHEIM (in my opinion, that’s throwing money away), but it’s important to avoid unknown or questionable sources.
Second, make sure to rinse your lava rock thoroughly. I’ve been buying from the same trusted supplier for years — the rock is great, but it needs a serious rinse. I usually do it in a big barrel in the yard on a sunny day. The amount of dust trapped in the pores can be surprising, and it’s definitely worth washing it out.
I personally use lava rock in my Fluval FX6, in an Aquael filter (Polish brand), and also in a trickle filter I built myself (which holds around 15 liters of lava rock). I’m very happy with the results. I prefer chunk sizes around 4–6 cm — smaller pieces tend to restrict water flow.
Please keep in mind this is just my humble opinion that I wanted to share with you.
Some lava rocks may contain heavy metals or other contaminants that can leach into the water and harm your fish. I’m not suggesting you need to buy branded options like EHEIM (in my opinion, that’s throwing money away), but it’s important to avoid unknown or questionable sources.
Second, make sure to rinse your lava rock thoroughly. I’ve been buying from the same trusted supplier for years — the rock is great, but it needs a serious rinse. I usually do it in a big barrel in the yard on a sunny day. The amount of dust trapped in the pores can be surprising, and it’s definitely worth washing it out.
I personally use lava rock in my Fluval FX6, in an Aquael filter (Polish brand), and also in a trickle filter I built myself (which holds around 15 liters of lava rock). I’m very happy with the results. I prefer chunk sizes around 4–6 cm — smaller pieces tend to restrict water flow.
Please keep in mind this is just my humble opinion that I wanted to share with you.
Where do these reputable online stores buy it from?I highly recommend buying it locally or from a reputable aquarium store online.
Post some pictures of your setup.
Sorry, I should have mentioned that I’m based in Poland. I usually buy lava rock on a local auction site called Allegro — you can think of it as the Polish version of eBay.
There are quite a few sellers offering lava rock from different sources — some specialize in aquarium or garden supplies. I’ve been buying from the same trusted seller for several years, so I feel confident about the quality.
Of course, it’s still a general-purpose product — not some $100 branded filtration media.
There are quite a few sellers offering lava rock from different sources — some specialize in aquarium or garden supplies. I’ve been buying from the same trusted seller for several years, so I feel confident about the quality.
Of course, it’s still a general-purpose product — not some $100 branded filtration media.
Lava rock probably has a great internal surface area, but that doesn't matter when it comes to filtration.
Water flows where resistance is lowest — around the media, not through it. In most cases, it's the external surface of the media that matters.
For example, PVC shavings are more effective than Siporax. [See: https://www.docdroid.net/wLLOb91/siporax-pdf]
All ceramic media are inefficient — 4 to 6 times less effective compared to K1 or foam.
Additionally, lava dust can shorten pump lifespan.
Water flows where resistance is lowest — around the media, not through it. In most cases, it's the external surface of the media that matters.
For example, PVC shavings are more effective than Siporax. [See: https://www.docdroid.net/wLLOb91/siporax-pdf]
All ceramic media are inefficient — 4 to 6 times less effective compared to K1 or foam.
Additionally, lava dust can shorten pump lifespan.