It can be tempting when walking on a beach or through a wood, to pick up some lovely bits of natural d?cor (free and for the taking of course) and to consider adding this to your tank at home.
Caution though! Not all of natures frequently abundant treasures are fish safe and some careful thought should be applied before adding such finds to fish tanks.
Generally speaking FK recommends completely inert decorations for aquaria unless the keeper is specifically trying to alter water chemistry and pH. This is usually done through the use of partial reverse osmosis water (RO) mixed with pre-treated tap water each week (to achieve softer water tanks) or by using crushed coral or oyster shell for example to reach harder pH levels. Safe Rocks
With many thanks to FK member Goldnugget for his pearls of wisdom here relating to rock issues
A common method is to try the ?vinegar test? on rocks. Add a splash of vinegar, if it bubbles then there are strong concentrations of carbonates present and this will increase the hardness of the water ? the acid reacts with the carbonate and releases CO2, which are the bubbles you see. Be careful though, this doesn't mean a rock is inert, merely that carbonate concentrations are high enough to cause a reaction. Regular water tests will soon tell you if your selected piece of rock is affecting the tank when you undertake readings each week before the water change.
Rocks such as slate, basalt, LFS bought ocean rock, marble, granite and some precious minerals such as amethyst etc are usually inert and so are safe (generally speaking most igneous and metamorphic rocks are safe). Rocks to avoid are carbonate based rocks such as limestone and some sandstones (depending on origin and composition), sandstones tend to act like sponges in an aquatic environment, soaking up minerals, toxins and biological matter you wouldn't want released into the tank.
Even slate on occasion can contain pyrites so may affect the water parameters. Often invisible to the human eye, pyrite forms due to iron minerals present in the original shale from which the slate formed. At high levels it appears shiny but may well go undetected at lower levels.
Rocks collected from a garden or a beach are generally not recommended as they can be contaminated (i.e. pesticides or fertilisers). Be aware that collecting stone or rocks from beaches may also be illegal - best leave it where it is. Safe Wood
As with rocks, the same goes for safe fish friendly wood but there are some staple varieties that are very safe. Bogwood
- Available from most good LFS. The real definition of bogwood is wood that has stood for years in an acidic peat bog and has consequently leached out its tannins and has acquired a dark colour. Bogwood hasn't rotted, because the low pH of a bog discourages fungal spores and most bacteria.
This needs soaking for a few weeks, maybe a bit more, unless you are seeking the ?dark water? effect. The remaining tannins will leach out, keep it a bucket and refresh when needed. An absolute must for any plec owner, whose fish need the Lignin in the wood to rasp and digest for health reasons. Tends to slightly soften water over time. Quite bulky though and will take up quite a bit of room in the tank. It will need pre-soaking so it sinks ? see below. If you don?t like the slightly brown tannin stain it generally leaves in the tank water for the first few months or so, the use of carbon in the filter will remove this. Remember to remove and replace carbon though frequently.Redmoor root
- Available from most good LFS. Nice twisty thin specimens taking up less room than bogwood. Generally reddish in colour with striking branch like roots. Safe for fish and shouldn?t affect water colour, once pre soaked ? see below.Mopani wood
? Available from most good LFS. This wood is hard and very tough. Often looks like a very thick root stem that has been sand blasted. It often sinks due to density without the need for pre-soaking which is good. Completely safe for fish. More bulky in the tank but unlikely to affect water colour.Pre soaking wood
Most new wood, except for Mopani usually tends to float for a while. It can take several weeks for it to sink properly. House it in a bucket or large enough container and cover with water. Weighting it down is preferable either by a large stone or more to hand, a big cooking pot (big bowls or casserole dishes work a treat!) Refresh the water when needed.New wood ? collecting your own
Not recommended by FK! Whatever the source, wood that is suitable for aquarium use must have first lost all of its greenwood and sap, which may take years and many types of locally found wood/sticks/brush wood are highly toxic indeed. LFS wood only. Fungi/fluff/white stuff on new wood
We get a lot of posts on this, but it is nothing to worry about. Sometimes patches of whitish fuzzy Saprolegnia appear on wood that's recently been placed in the aquarium. Though wood in oxygenated water at neutral pH values is almost always decaying, however slowly that may be happening, you don't want to encourage visible patches of fungus. Resist any temptation to attack the fungus by adding something toxic to the water though.
Be patient. As the aquarium matures, fungus on wood won't normally trouble you, in fact the fish will eat it or it will simply disappear given time. If you really don?t like the look of this temporary fluff though, it can be easily be rectified by removing from the tank and giving a quick wipe with a clean (unused) scourer of some kind.