River rocks

[Geochurchi]

Hi, I have made a terrible mistake by putting some river rocks in my tank,even though they were boiled they have produced a terrible green algae problem which I have been unable to clear up even after completely taking the tank apart an cleaning it,tried black out procedure to no avail,and weekly water changes. HELP!

Thanks

[Cermet]

What are your tank's water parameters: nitrate (esp.) Phosphate if available (most don't have that kit.) How often and how large are the water changes. Boil rock (any length of time) kills everything but rocks can provide critical nutrients that algae can use. As always, algae grows when there are other issues that upset the balance of the system. With this info, more can be suggested.

[Cliff]

+1 to the above

Rocks typically do not cause algae, a imbalance between the nitrate/phosphate levels and light is usally what will give you a lot of algae.

[talldutchie]

Some rocks can add just enough Silicic acid to tip the balance and give the brownish/green algae a boost.

Even then, if that is a problem then something else will have been wrong already

[Geochurchi]

All of the parameters of the water are the same as they have been for at least 2 years Nitrate 0. Nitrite. 0, no Phosphate test available at this time,I do believe my next best set now having read your reply will be to take a water sample to Fish store and have it tested.

[Cliff]

You have to keep in mind that aquariums with bad algae breakout will typically test and show lower levels of nitrates and phosphates making you believe you do not have a lot of either in the water. That is miss leading as the algae will consume large amounts of nitrates and phosphates instantly so a large amount of them will never show up on your test kits

It’s the same principle as testing for ammonia and nitrites in a properly stocked and cycled aquariums. When you test for those two elements you will get a reading of 0ppm. That is not because your fish stopped producing waste, it is because your bacteria removes them almost instantly so there is nothing left for your test kits to pick up on.

I would suggest assuming your set-up is producing more nitrates and phosphates than what your test results are showing. The below is a list of actions that I have learned to work well when dealing with algae:
1) Larger water changes. Try increasing the amount of water you change each week or the number of weekly waterchanges you complete
2) Clean your filter media in old tank water monthly
3) Try feeding less. Most people even fast there fish one day a week
4) Try cutting back a little on the light period
5) Do not allow your tank to get direct sunlight.