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Jan 11, 2008
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Hello all and I wonder if you can help. For reasons too long to go into I changed my gravel. I used Pets at Home own gravel. I washed it thoroughly and the water was clear and I still kept rinsing it though to make sure. Then set up the tank again. the following day the water looked a bit cloudy and then a short while later looked brownish and my two beautiful congo tetra were dead - I had had then for about 2-3 years. I got the spare tank and set that up and transferred the fish over (three quite large cichlids, plec and two small tetra) no other fish as the cichlids are getting quite big) I washed the gravel again and then boiled it for a couple of minutes then let it cool and then rinsed it again. (washing in a bucket of water pouring the water out repeating a few times and then putting small amounts into a sieve and rinsing under a running tap)

I left the tank set up again, without fish for a couple of days, and then took out all the water, changed the poly pad and refilled, then after a few hours put the fish back in. One of the tetra died just after putting into the spare tank, but the others seemed ok. After about three days the water started to look discoloured again and the fish looked distressed and gasping for air. I got the spare tank out again and transferred the fish. this was last night and they seem ok in the spare tank.

I will get rid of this gravel as it is the only thing I can think of that has caused the problem - there is nothing else happened. The only other information, which sounds very strange and it did not register with me at first but the gravel had a smell of marzipan when i opened the package. I assumed it was the plastic container it was in and did not think much about it at the time. However after i boiled the gravel - the boiling water had a smell of marzipan.

Is there anyone who has had a problem with this gravel before and can give any advice for when I put new gravel in again. (I have been keeping fish on and off for about 30 years and never had a problem with gravel before)

thank you

how bizzare, ive never heard of gravel causing this effect before, what were you using before the change? hopefully someone will be along with a idea as to what happened
Is the gravel the smooth fluorescent colour coated kind? If so are there any signs it is peeling or coming away from the stones?

Are both tanks fully cycled?
hello and thank you both, the original tank where the problem occurred has been going for years. I do a 10% weekly change and rinse out the three main filters in tank water about once a month (just a quick rinse) the carbon is changed about three times a year and the polypad every week. I only clean out the tank fully about twice a year and save some of the existing water to put back in. I use stresscoat at every water change and full clean out. The water is always crystal clear and no fish problems at all.

The spare tank is normally kept in our loft (we upgraded to a larger tank a few years ago) I just put in fresh water with lots of Stress coat and a much stronger aerator/filter.

The tank I have is Jewel and the filters/heater and pump are all contain in a black plastic box in the corner of the tank.


Sorry did not answer your question properly.

I did have sand in before and then I moved to this which is the size of pea gravel and smooth colours brown shades. bought as I said at Pets and packaged in their plastic bag. No peeling - the stones look perfect.
Sounds like you've removed your friendly bacteria from your filter by changing the filter pad and now you have an uncycled tank. Also, did you refill the tank with dechlorinated water? Water that has not been dechlorinated should never touch your filter.
If the tank has the Juwel filter, it is normal to change the white pad every couple of weeks as it gets clogged quickly and won't wash more than once. There should be plenty of sponges and possibly a box of ceramic media in there as well as the white pad.
Shea, just to check, it was just the white pad from the Juwel filter you changed?

If the gravel smelled of almonds, it doesn't sound right. None of the gravel I had in the past (before I changed to sand) ever smelled of anything.
I always use the tank water to rinse the sponges and through habit - change my white polypad filter every week.
After the first problem with the discoloured water I did not want to rinse the filters in this water and so made up boiled cooled water with stress coat in it to rinse the sponges, which I normally would never ever do but as I say did not want to use the discoloured water and used a new white polypad filter.

the smell has worried me - the gravel never had the smell, just the bag when I opened it and then the water I boiled the gravel in.

I have emailed Pets at Home but they have not replied to me. I also spoke to a young lady in the shop where I bought it from and to be honest she did not seem to care. (which is why I emailed them to see if I could get some kind of response as to what could have caused this).

I do appreciate your interest
thank you
That's very odd.. I hope you get a response from them soon! They should reimburse you for the poor fish deaths too :(
I just bought the Pets at home small brown pea gravel, and as soon as i opened the bag i smelled almonds (marzipan smell )  
i have owned fish tanks for over 10 years and am setting up a new one this is the first time out of 4 baggs of gravel that i have ever found one that had such a smell , normal pea gravel should just smell of , well gravel , ( slightly dusty earthy smell) 
after smelling this and reading this page , i have decided to take the gravel back to the store for a refund. i am fortunate i did not write this off as just the smell of gravel , 
the marzipan smell comes from almond oil , which is a nut oil , found by pressing nuts to extract it , it should not be in a normal water course in oil form , and as an oil it would surely damage the fish any.   
can someone please reply and tell me what you think of this

Additional: one other point struck me as peculiar , when purchasing , we asked if the this was the gravel they had in the instore tanks , they replied no we have separate gravel for that. 

so the gravel is good enough to sell but not good for them to use ?? 
UPDATE : phoned Pets@Home today and explained to their instore "expert" he said bring it down to the store for them to look , when i got to the store the chap  was astounded by the strength of the smell, 

he admitted that when we spoke on the phone he thought i was talking about a light wiff , not a full on bottle of almond flavoring that hits u in he face , 

he opened up another bag and that was even worse , even a smaller bag of the same gravel same smell , 

They have withdrawn it from sale at the local store , pending further investigation , gave me a full refund and a bag of free sand , that did smell ok although i will be suspicious of their stock from now on..

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