Ryno

Ours can get a little slimy from time to time but we use leisure time spa algacide and that does the trick for about a month, the ionizer helps throughout the process on a daily basis. are all your other levels in balance? Are you adding anything in addition to bromine and water adjustments?

Adding bleach is okay after you build up 20-30 CYA from adding Dichlor. You don't want to start a fresh fill with bleach without first adding a week or two of Dichlor to build up those levels appropriately. Additionally, I found that a specific product from Clorox to be the plainest in ingredients. It's Clorox 30966 and contains just the disinfectants needed without all the extra softeners, polyvinyls, fragrances or lauramines that other products the Clorox offers has. Here's the list of ingredients from this product on their website. Just keep in mind that bleach can adjust your pH so keep an eye on that every 2 weeks. I hope this helps! https://www.thecloroxcompany.com/en-us/what-were-made-of/ingredients-inside/cloroxpro/clorox-commercial-solutions-clorox-germicidal-bleach1-concentrated-44600309668/

Update: After doing a fair bit of research on bleach composition, I found and switched to Chlorox Germicidal Bleach 30966, as it contains no poly’s and has 8.25% concentration. Seems to be the best on the market for what we’re trying to accomplish but limited to where you can purchase it. Couldn’t find it at a standard hardware store. I’m adding just under 4oz daily to bring my chlorine levels to 3% after adding dichlor for a week and getting my CYA to just over 30ppm. My CD is still high (nearly zero 24 hours later) and unsure as to why but assume it’s because of the cedar. Would love to hear why if anyone knows for sure as I would love to maintain a chlorine level daily as to add less bleach. I am also still using the tub about 3x per week and notice the tannin leaching but it does appear to be tapering off. 2 weeks after the recent water change, I can still see the bottom of the tub but have noticed it to be more cloudy. I have replaced water on average every month but was close to 2 months on prior fill.

I’m thinking the leeching of tannins is what’s causing our chlorine demand. Once the tannins slow down and the water stays clear, I’m expecting standard CD going forward - I guess time will tell but I’ve been adding 4oz or so each morning bringing up my FC to roughly 2-3ppm and I add the same amount after each use. Because bleach has been hard to find recently, I’ve switched to Clorox bleach with cloromax - regular unscented 6%. Are there any concerns with bleach with cloromax or should I try and find Clorox bleach regular (it seems like everything has cloromax in it now)? The other bleach is Clorox germicidal bleach unscented 6%. Is there a difference?

Thanks for this post! It’s well thought out and it’s exactly what I’m going through now with my new cedar hot tub that’s a month old. I would love to hear what you figured out and how you resolved the chlorine demand issues you were having. I’m also going to the dichlor/bleach regimen but seeing chlorine disappear entirely each day and concerned about it attacking and damaging the wood. I would hate to bleach out the inside of the tub by adding too much.

Thanks Emerald. That’s great insight. That’s almost exactly how I approached it up until this point were I became overly concerned with how fast the chlorine was disappearing. Didn’t want to sit in a tub of water with some nasties hiding in it but don’t want to keep chlorinating to the point of wood damage. In a little over a week my CYA is at 50 or 60, and I know that’s high because of the dichlor shock I did. But I should be able to get a chlorine demand that’s less than 50%, right... Right?

So this exact same thing happened to our tub. Brand new and almost 4 weeks in. The first few weeks were great, no issues at all. We dumped the initial water as it had turned very dark with tannins and upon refilling, we started to experience slime on the benches and side wall. Drained and scrubbed it all out with oxiclean and filled again. Used the tub twice since but noticed my chlorine levels were disappearing overnight. I super chlorinated to 13ppm but that went to zero as well. Seeing a noticeable scum line when jets are on high that’s brownish in color. Otherwise tub water looks good and filter is super clean. What could be happening? Ecstatic, I would love to hear your regimen and decontamination. I’ve read the bleach method by Nitro and ChemGeek but worried if it would cause major issues with the wood, like bleaching it out or causing it the crack. I do plan on using the swirl away product and dump but confused on next steps to prevent this from happening again.

Sorry, CD is my Chlorine Demand. Using up large amounts over a short period of time is concerning. I have the ionizer running with 0.2ppm copper in the water but chlorine is going from high levels to none in 18 hours.

So I went ahead and did a dichlor chlorine shock to see what would happen. Tub was freshly filled 1 week ago so not worried about CYA but wanted to to get stable readings and a consistent CD. Added 1.7oz of dichlor bringing my chlorine level to 13ppm. 4 hours later my levels were 6ppm, 13 hours later it was at 0.4ppm. So my CD is definitely 100%. Brought levels back up this morning to 6.5ppm and will see how long it takes to disappear. My guess is there must be something growing in the tub (although I can’t see it) or is it just attacking the wood? That amount of chlorine will inevitably damage the wood if I keep on adding that amount.

I performed another refill on the tub and removed the slime build up with oxyclean and water. Rinsed and flushed. Brought water chemistry back to stable later that day. I went ahead and purchased leisure time algaecide to periodically treat any slime build up and will see if that does the trick if it returns. I’m also still tinkering with FC levels and am finding it to be a challenge. I’ll add the recommended dosage (1tbsp dichlor for the 700g tub) and with the water nice and clear, I’m getting a reading of about 1.6ppm 30 min later, which was a bit better than my past readings on my initial 2 fills (probably due to leeching). Fast forward to about 8 hrs later and I’m getting a reading of zero. I want to add more but I don’t want to add too much as my thought process is the chlorine is attacking the wood and I just keep on dumping it in. Should I try to do a “shock” and dump in like a triple dose and get the FC levels to around 6ppm and see what happens and how far and fast the levels drop? I just don’t want to add too much as to cause irreparable damage to the wood. What are your thoughts?

I have looked at alternative options instead of just using Dichlor but have not considered a UV/peroxide system. The only one that looked promising was switching to a dichlor/bleach method after you build up your CYA levels. How long that takes? IDK. This seems quite doable as bleach is inexpensive and can work without implementing any new "systems" being installed. From what I understand, chlorine will attack the wood if there's no other bacteria for it to kill but it also burns off quickly and doesn't stick around like bromine would, which can lead to more damage of the wood even if used properly. I also like your suggestion about keeping ozone inside the piping as everything I've read causes issues in wood tubs. However, my plumbing run is extremely short as the pump/heater/plumbing is all within 15" of the tub itself, just a few feet of runs to get to each of the jets.

I purchased my tub from www.redwoodsaunas.com out of Texas. I live in CA. The owner Jim was extremely helpful and guided me through the process and customization of my tub. Highly recommend them, courteous, patient, and a high quality hot tub. It’s 6 feet in diameter and holds around 700 gallons (42” water depth). I had it designed with 8 jets (2 each in four locations) and all the equipment resides in a custom enclosure that surround the tub. It’s absolutely beautiful and a focus in our backyard now. The pump is 2hp and all the plumbing is by waterway jets. Very happy with it. We filled it about 3 weeks ago, dumped the first batch of water and had the second fill now for 2 weeks. Still very heavy leeching. The first week we doubled the chlorine daily and added leisure time bright and clear each day to speed up the process of the leeching according to the manufacturer. On second fill, I added Pro Team Spa Gentle Spa for bather comfort and water stabilization and that appears to have worked well. The ionizer appears to also be working well and I’m getting a residual copper reading of about 0.2ppm after a week. I understand this can take some time to build up but unsure how long. I balanced the water using a Taylor K-2006 test kit and my readings are as follows: 110 alkalinity (130-140 at first but balanced out) 7.4 pH 150 calcium hardness (used a calcium booster to achieve this as our CH was extremely low) Adding about 1tbsp chlorine (dichlor) daily and after tubing. I’m averaging about 0.2ppm chlorine in the morning based on what I can read from the test kit. About 0.8ppm after 30 min of adding it. I’m also debating increasing the chlorine due to a slime that I can feel on the benches near the walls of the tub and the outer edges of the floor that occurred yesterday. Not sure what it is. Worried about over chlorinating and pulping the wood but want to resolve the slime as well. I feel my levels are spot on and according to the test kit, it’s perfectly balanced. Hopefully we can come together and find solutions for our tubs that other can benefit from and looking for any knowledge within the community.

Would love to hear how much chlorine you use in your cedar tub to bandage your bather load. I am also shocked that it’s still leeching tannins 5 years later. What does you daily/weekly management look like? Beautiful tub btw!

I have just completed the order of a new custom cedar tub and eager to get going on water chemistry. I have read through plenty of forums, spoke with many different people around routine maintenance, and boy - it’s all over the map, especially when it comes to wood tubs. Many wood tub dealers recommend bromine and ozone solutions but I’m staying away from those and have invested in an ionizer and chlorine solution only. Mainly based on what I’ve read here. I would love to hear a detailed regimen from first fill to daily/weekly maintenance. The tub is just shy of 750 gallons so I’d rather not “experiment” and have to dump all that water and start over. Our bather load will be 2 people 3-4x per week and 4-6 people 2-3x per month. I’m looking to maintain the tub for as long as possible while keeping a routine easy enough to manage each week without it consuming me. Who can show us the way?